Course Profile   Functions, Grade 11, University/College Preparation, Catholic and Public

 

Unit 3:  Financial Applications of Sequences and Series

Time:  25 hours

 

Activity 3.1 | Activity 3.2 | Activity 3.3 | Activity 3.4 | Activity 3.5 | Activity 3.6 | Activity 3.7 | Activity 3.8 | Activity 3.9

 

Unit Description

Students work with arithmetic and geometric sequences and series. This knowledge serves as the basis for applications in the field of personal finance. Students develop the formula for compound interest and solve problems related to compound interest and annuities. As skills are developed, students use spreadsheets to investigate the cost of borrowing when interest rates, compound periods, lending terms, etc., are varied. The activities are designed to reflect the type of decisions that students are likely to face in the future. Students apply skills with linear and exponential functions. Students are expected to summarize the results of their investigations in a clear and concise manner.

Unit Synopsis Chart

Activity

Time

Expectations

Assessment

Tasks

3.1 Investigating Attributes of Sequences

150 min

FAV.01, FA1.01, FA1.02

Inquiry, Communication

Work with sequences

3.2 Summing Up: Arithmetic Sequences and Series

150 min

FAV.01, FAV.02, FA1.04, FA1.05, FA2.04

Knowledge, Application, Inquiry

Develop formula for arithmetic sequences and series

3.3 Compound Interest: Exploring Geometric Sequences

150 min

FAV.01, FAV.02, FA1.03, FA1.04, FA2.01, FA2.02, FA2.05

Knowledge, Application, Communication

Use a financial application to investigate geometric sequences. Develop the compound interest formula

3.4 Applications: Finding the Amount and the Present Value of a Long Term Investment

75 min

FAV.02, FAV.03, FA2.02, FA3.01, FA3.02

Knowledge, Application

Extend knowledge of the compound interest formula and introduce financial applications of a graphing calculator

3.5 Introduction to Geometric Series

75 min

FAV.01, FA1.05

Knowledge, Application

Develop the formula for the sum of a geometric series

3.6 Applications: Finding the Amount and the Present Value of an Annuity

150 min

FAV.02, FAV.03, FA2.02, FA2.03, FA3.05

Inquiry, Communication

Apply geometric sequences and series to finding the amount and present value of an annuity

3.7 What Happens When?: Changing the Time, Rate and Amount

150 min

FAV.03, FA3.01, FA3.05

All

Use financial applications of a graphing calculator to investigate the effect of changing conditions when borrowing and saving

3.8 Mortgages: How They Work

150 min

FAV.03, FA3.02, FA3.03, FA3.04, FA3.05

Application, Communication

Use technology to generate amortization tables

3.9 Financial Decision Making: A Case Study

300 min

All

All

Summative Assessment Activity

Note: 150 minutes has been allotted to practice essential skills, review and to do other assessments.

Assessment & Evaluation of Student Achievement

Some of the problems contained in the activities can be used to assess the inquiry process. Short quizzes can be used to assess Knowledge/Understanding and Application. Teachers might choose to give a short quiz on Arithmetic Sequences and Series, another on Geometric Sequences and Series and a third on the Compound Interest Formula and applications of the formula. In addition (or alternatively) a test on Activities 1 to 5 might be given. In Activities 6 to 8, students will apply skills from Activities 1 to 5 to investigate finance. Activity 9 is designed as a culminating assessment tool for the entire unit, with emphasis on financial applications. Communication skills should be assessed continuously throughout the unit. Students should use proper mathematical form, appropriate notation and explain their answers in a clear and concise manner. The Inquiry Rubric and the Communication Rubric produced by OAME are resources to use to assess student achievement.

 

Activity 3.1:  Attributes of Sequences

Time:  150 minutes

Description

Students work with a variety of sequences. Arithmetic and geometric sequences provide a background for future financial applications and the Fibonacci sequence, as well as the sequence created by the Tower of Hanoi problem are included for interest and to emphasize that there are a variety of sequences that can be studied. Students are also introduced to notation used for sequences to be applied later with financial applications.

Strand(s) & Learning Expectations

Strand(s):  Financial Applications of Sequences and Series

Overall Expectations

FAV.01 - solve problems involving arithmetic and geometric sequences and series.

Specific Expectations

FA1.01 - write terms of a sequence, given the formula for the nth term;

FA1.02 - determine a formula for the nth term of a given sequence.

Prior Knowledge & Skills

Understanding linear and exponential relations may help in transferring knowledge to relations studied in this activity.

Planning Notes

·         Provide the students with a copy of the student activity.

·         Use of a graphing calculator may be helpful, but is not essential. By graphing the relationships students can determine if the sequences are linear, quadratic, exponential, or other.

Teaching/Learning Strategies

Students should work individually or in pairs to work with the sequences. Discussion of the Fibonacci sequence (introduced in question 3) and the Tower of Hanoi problem (introduced in question 4) will ensure that students do not assume that the only types of sequences are arithmetic and geometric.

Student Activity

Investigate the following situations.

1.   Fill in the chart below. The triangle is an equilateral triangle.

Side Length

1 cm

2 cm

3 cm

4 cm

5 cm

Perimeter

 

 

 

 

 

 

a)   Predict the perimeter of the triangle if the side length is 20 cm.

b)   Identify the type of relationship between the perimeter and the side length.

c)   Create a formula that can be used to find the perimeter of an equilateral triangle with
side length n.

d)      Verify that your formula works.

2.   The cells in a culture divide every hour.

a)   If there are 500 cells now, how many cells will there be in 1 hour?

b)   Create a table showing the number of cells at the end of each hour for 5 hours.

c)   What type of relationship exists between the number of cells and the time?

d)   Predict the number of cells after 8 hours.

e)   Create an equation that relates the number of cells to the time.

f)    Verify that your formula works.

3.   You have 12 sticks of different whole number lengths in a bag. What must their lengths be if, when you pull out any 3 of them, you cannot make a triangle? What is the shortest length of the longest stick?

4.   Tameez has a board with 3 pegs. The first peg has 5 flat blocks, all of different sizes, arranged by size with the smallest on top and the largest on the bottom. He wants to move these blocks to the third peg in a minimum number of moves. He has set up rules for himself which include:

i)    only 1 block can be moved at a time.

ii)   A larger block cannot be put on a smaller one.

a)   What is the least number of moves Tameez can take to move the blocks? Explain your reasoning.

b)   Predict how many moves would be required if there were 10 blocks on the first peg.

c)   What is the general relationship between the number of blocks and the number of moves required?

5.   In each of these examples a pattern can be found. Try to find the pattern and determine the next two terms for each of the following.

a)   1, 3, 5, 7, __, __

b)   12, 24, 48, __, __

c)   , , , __, __

These are examples of sequences of numbers. A sequence is a set of numbers, shapes, letters, etc. that are in a distinct or recognizable pattern.

6.   In the sequence 3, 6, 9, 12, 15, 18… the fourth term is 12. We write this as t4 = 12. State the values of t2 and t6. The terms of this sequence represent the perimeters found in question 1 above. We found that P = 3n where n represents the side length. For the sequence 3, 6, 9, 12, …

tn = 3n. Find t30 and t50

Teacher Facilitation

The sequence developed in question 3 of the student activity is the Fibonacci Sequence. Two of the follow-up questions also result in the generation of this very interesting sequence. After completing the student activity present the students with some examples where, given a general term, they must find the first few terms (see follow-up questions). Students should also be presented with examples where, given the general term and the value of the term, they can determine where the term is located in the sequence.

Follow-up Questions

1.   You have 7 steps to climb. You can go up 1 step or 2 steps at a time. In how many different ways can you climb the steps. Use the chart below to help organize your work.

Number of steps

1

2

3

4

5

6

7

Number of possible ways

 

 

 

 

 

 

 

2.   Using nickels and dimes only, in how many different ways can you make up various sums of money?
(i.e., $0.05, $0.10, $0.15, $0.20, $0.25, $0.30); etc.

3.   Given the general term, state the first 4 terms of each sequence:

a)   tn = 3n + 1                                b)         tn = 2n

4.   Find tn for each of the sequences in question in the previous activity.

Assessment & Evaluation of Student Achievement

Students’ ability to read and interpret directions could be informally assessed as they work. Students could be asked to write a journal entry describing the results of their investigation. Student work on questions 3 and 4 could be collected and assessed using a rubric which focuses on inquiry. Where verification or explanation is required, communication could be assessed.

Accommodations

Use concrete materials for students to better understand the activity.

 

Activity 3.2:  Summing Up: Arithmetic Sequences and Series

Time:  150 minutes

Description

Students investigate, through financial applications and other contexts, arithmetic sequences and series and develop the formulas for the general term of an arithmetic series and the formula for the sum of the terms of an arithmetic sequence. During the investigation, students make a connection between arithmetic sequences and linear growth.

Strand(s) & Learning Expectations

Strand(s):  Financial Applications of Sequences and Series

Overall Expectations

FAV.01 - solve problems involving arithmetic and geometric sequences and series;

FAV.02 - solve problems involving compound interest and annuities.

Specific Expectations

FA1.04 - determine the value of any term in an arithmetic or a geometric sequence, using the formula for the nth term of the sequence;

FA1.05 - determine the sum of the terms of an arithmetic or a geometric series using appropriate formulas and techniques;

FA2.04 - demonstrate an understanding of the relationships between simple interest, arithmetic sequences and linear growth.

Prior Knowledge & Skills

·         first and second differences to identify whether a relationship is linear or quadratic

·         notation associated with sequences and series

·         use of a graphing calculator

Planning Notes

·         A brief review of simple interest may be necessary before beginning this activity.

·         Part A: Students work independently on the investigation.

·         Part B: Prepare an overhead with the problem only. Have the students work in groups of four or fewer to investigate the problem.

·         It would be helpful if students had access to graphing calculators.

Teaching/Learning Strategies

Part A: Teachers may need to emphasize the relationship between arithmetic sequences and linear growth. Ensure that students have obtained the correct formula for the general term of an arithmetic sequence.

Part B: Encourage students to develop a strategy to find the number of handshakes accurately. After the students have worked in groups, discuss the various strategies. Be sure to discuss the strategy of introducing the people to the room one at a time in order to develop the concept of an arithmetic series.

Student Activity

Part A

Carolyn received a gift of $1000 from her grandmother when she graduated from Grade 8. The money is to be invested to help Carolyn pay for university when she graduates from high school. She buys an investment that pays 4% per year simple interest. Complete the chart below to determine the amount that Carolyn will have at the end of each year for the next five years.

End of Year

Annual Interest

Total Amount

1

40

1040

2

40

1080

3

 

 

4

 

 

5

 

 

1.   Predict the amount that Carolyn would have if she kept the investment for ten years. On what are you basing your prediction?

2.   What is the type of relationship between the number of years she has the investment and the total amount? Hint: Examine the first differences.

3.   Determine the equation that best models the relationship between the year and the total amount.

4.   Use the equation to predict the year that Carolyn will double her investment.

5.   The total amounts that she has at the end of each year can be written as a sequence similar to the sequence   7, 10, 13, 16, 19, 22, …

This sequence can be written 7, 7 + 3, 7 + 3 + 3, 7 + 3 + 3 + 3, 7 + 3 + 3 + 3 + 3, … or using the notation developed in Activity 3.1.

            t1 = 7 + 0(3)

            t2 = 7 + 1(3)

            t3  = 7 + 2(3)

            t4 = 7 + 3(3)

            t20 = 7 + _(3)

            tn = 7 + (    )(3)

Simplify the last term of this sequence. This is called the general or “nth” term of the sequence.

6.   Write the total amounts that you found in the chart above as the terms of a sequence.

7.   Find the “nth” term using the method used in question 5. Compare this to the equation found in question 3.

8.   Use this method to find tn for each of the following sequences.

a)   -10, -6, -2, 2, 6, …

b)   12, 8, 4, 0, -4, …

c)   , 1, , 2, …

The sequences in this section are called arithmetic. Describe the properties of any arithmetic sequence.

9.   Give an example of an arithmetic sequence. Explain why you think it is arithmetic.

10.  In general, every arithmetic sequence has a first term, a, and the difference between successive terms is a constant, d. Complete the missing information below.

            t1 = a

            t2 = a + d

            t3 = a + 2d

            t4 = a + 3d

            t25 = a + (    )d

            tn = a + (    )d

The last term is the general term of any arithmetic sequence.

Part B

1.   How Many Handshakes?

a)   Determine the number of handshakes required in a room that contains 5 people if each person shakes hands with every other person once?

b)   If one more person enters the room, how many more handshakes will occur? What is the new total number of handshakes? Predict the number of handshakes that will occur if there are 10 people in the room.

You may find the following chart helpful to organize your work

Number of People

Number of Handshakes

Total

1

0

0

2

0+1

1

3

0+1+2

3

4

 

 

5

 

 

c)   Identify the type of relationship that exists between the number of people in the room and the total number of handshakes.

d)   Find an equation that best models this relationship. The number of handshakes if there are 5 people in the room can be found by adding the following 0+1+2+3+4. The numbers 0,1,2,3,4 are the terms of an arithmetic sequence. Explain why. When the terms of an arithmetic sequence are added, the result is called an arithmetic series.

e)   The number of handshakes required if there are 10 people in the room can be found be adding the terms of the arithmetic series 0+1+2+3+4+5+6+7+8+9.

 

S10 = 0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9

S10 = 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 + 0

Adding these two rows, we get

            2S10 = 9 + 9 + 9 + 9 + 9 + 9 + 9 + 9 + 9 + 9

            2S10 = 10(9)

            S10 =

 = 45

 

f)    Use a similar process to find the total number of handshakes required if there were 20 people in the room, 50 people in the room. Find the total number of handshakes required if there are n people in the room.

2.   The same method can be used to find the sum of the terms of any arithmetic series.

a)   Use this method to find the sum of the terms of the following arithmetic series:

i)          Find the sum of the first 9 terms of the series 9 + 11 + 13 + 15 + 17 + 19 +…

ii)         Find the sum of the first 10 terms of the series 10 + 12 + 14 + 16 + 18 + 20+…

b)   Note that the sum of the first 5 terms can be found by the following S5 =  Create a formula to find the sum of the first 8 terms.

c)   Create a formula to find the sum of the first n terms.

d)   Recall that t1 = a, and tn = a + (n-1)d for an arithmetic sequence. Verify that the following formula represents the sum of n terms of an arithmetic series.

S =

e)   Verify that S10  in the previous example is 45 by letting a = 0, and d = 1.

3.   Friedrich Gauss was a famous Mathematician. When he was 10 years old his teacher gave him the problem of adding the whole numbers from 1 to 100. The problem was meant to keep him busy for several minutes, but he immediately said that the sum was 50(101). Explain how he might have used the Sn formula to get his result.

Teacher Facilitation

Students need to develop skills with arithmetic sequences and series. At the end of each part of the activity the concepts should be summarized and additional problems assigned from the students’ text.

Extension

S10 = 0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 can also be written . This notation is called Sigma or Summation Notation.

 

1.   Write the series represented by

a)                     b) 

2.   Write the following series using summation notation

a)   1 + 3 + 5 + 7 + 9 + 11                b)  4 + 6 + 8 + 10 + 12 + 14 + 16 + 18

Assessment & Evaluation of Student Achievement

Learning skills, such as teamwork, could be informally assessed while students work in small groups. After students have had an opportunity to consolidate skills on arithmetic sequences and series, teachers could give a short quiz to assess Knowledge/Understanding. Teachers might collect solutions to questions 1 and 3 and assess Thinking/Inquiry and Problem Solving. Questions 2a and 2e could be used to assess Application.

Accommodations

·         Handouts should be provided for students who have difficulty reading from the overhead screen.

·         Partner student within teams to provide support for students who require peer assistance

 

Activity 3.3:  Compound Interest: Exploring Geometric Sequences

Time:  150 minutes

Description

Students develop the concept of a geometric sequence through the use of compound interest. They then develop the formula for the general term of a geometric sequence using patterns discovered. The formula will be applied to develop the compound interest formula.

Strand(s) & Learning Expectations

Strand(s):  Financial Applications of Sequences and Series

Overall Expectations

FAV.01 - solve problems involving arithmetic and geometric sequences and series;

FAV.02 - solve problems involving compound interest and annuities.

Specific Expectations

FA1.03 - identify sequences as arithmetic, geometric or neither;

FA1.04 - determine the value of any term in an arithmetic or a geometric sequence, using the formula for the nth term of the sequence;

FA2.01 - derive the formulas for compound interest and present value, the amount of an ordinary annuity, and the present value of an ordinary annuity, using the formulas for the nth term of a geometric sequence and the sum of the first n terms of a geometric series;

FA2.02 - solve problems involving compound interest and present value;

FA2.05 - demonstrate an understanding of the relationships between compound interest, geometric sequences, and exponential growth.

Prior Knowledge & Skills

·         simple interest formula

·         use of a graphing calculator and/or spreadsheet software

Planning Notes

·         Students need access to a graphing calculator or spreadsheet software.

·         Students can work individually or in pairs on the activity.

·         Spreadsheets might be used to generate tables.

·         The rule of 72 might be used where doubling applies.

Teaching/Learning Strategies

When students are completing the chart in the activity, suggest that they look for efficient ways of calculating the new principal. This will lead to the development of the geometric sequence. After students have completed Part A, the teacher should assign some follow-up questions from the text, or other resources. Before beginning Part B, discuss the vocabulary related to compound interest. Define conversion or compound period and discuss the meaning of statements like “interest is compounded semi-annually”. Students may need some help developing the sequences in Part B. Make sure that they have the correct meanings for the variables in the compound interest formula.

Student Activity

Part A

In Activity 3.2, Part A, Carolyn placed the money her grandmother had given her in an investment that paid 4% per year simple interest. Understanding simple interest is very important to understanding how interest is actually calculated. It is very rare that an investment like the one in Activity 3.2 would be used. Usually interest is calculated on a regular basis and deposited in the account. The next time that interest is calculated the principal has increased. This is called compound interest because interest is paid on the interest that has been deposited. Complete the chart below to determine the amount that Carolyn will have at the end of four years if interest is 4% per year, compounded annually, and the interest earned is deposited at the end of each year.

Time (years)

Principal at the Beginning of the Year

Interest for the year

New Principal at the End of the Year

Now

-

-

$1000.00

1

$1000.00

1000(0.04)(1) = 40

1040.00

2

1040.00

1040(0.04)(1) = 41.60

1081.60

3

 

 

 

4

 

 

 

1.   Compare the amount she has at the end of four years to the amount you found in Activity 3.2, Part A.

2.   Determine the type of relationship that exists between the number of years that have elapsed and the total amount of money that Carolyn has accumulated.

3.   Use a graphing calculator to find an equation that best models this relationship.

4.   Predict the amount that Carolyn will have at the end of 10 years.

5.   Determine approximately how long it will take for Carolyn to double her money. Can you find more than one method of doing this?

Consider the sequence below:

1000,          1000(1.04)        1000(1.04)2,      1000(1.04)3,      1000(1.04)4

6.   Calculate the value of the 5 terms of this sequence.

7.   Compare the values to the “New Principal” in the chart above. What do you notice? Explain.

8.   Use the pattern in the original sequence to calculate the amount that Carolyn will have at the end of 7 years.

9.   Use the pattern to develop a formula for tn. Compare this to the regression equation found above. Explain what you found.

The sequence above is called a geometric sequence. Describe the properties of a geometric sequence.

10.  Give an example of a sequence that is neither arithmetic nor geometric. Explain why they are not.

11.  The geometric sequence   3, 6, 12, 24, … can be written in the form 3,3(2), 3(2)2, 3(2)3,… Find the value of the 5th term of the sequence. Find an expression for tn .

12.  Any geometric sequence can be written in the form a, ar, ar2, ar3, ar4, … a is the first term and r is the ratio of successive terms. Find an expression for tn.

Part B

In the first part of this activity you developed the formula for the nth term of a geometric sequence by looking at a problem involving compound interest. You discovered that the first term of the sequence
1000, 1000(1.04), 1000(1.04)2,  1000(1.04)3,  1000(1.04)4, is the principal deposited and the remaining terms represent the amount of money that has accumulated at the end of each year for 4 years.

Write a sequence that represents the amount of money that will accumulate if $5000 is invested at 6% per year, compounded semi-annually. Determine tn. In this case, what does n represent?

Write a sequence that represents the amount of money that will accumulate if $10 000 is invested at 8% per year, compounded quarterly. Determine tn. What does n represent?

Write a sequence that represents the amount of money that will accumulate if the principal is P and the interest rate per year is r. Interest is compounded monthly. Determine tn. What does n represent?

The compound interest formula is A = P(1 + I)n. Explain what A, P, I, and n represent.

Follow up Questions

At the end of each part of the activity, assign related questions. Some additional examples may be necessary. At the end of Part A, present the students with several different sequences (many examples will be available in the texts) and have them identify the type of sequence. Discuss how the formula for compound interest can be rearranged to find the present value of an investment or loan. Assign related questions for the students to develop skills.

Assessment & Evaluation of Student Achievement

Communication skills might be assessed after having the students write a journal entry summarizing their findings. Informal assessment of Learning Skills should be ongoing. Teachers could assign and collect solutions to a problem that requires the use of the compound interest formula to determine whether students are able to apply their knowledge to problem solving. Solutions to question 5 could be completed in a variety of ways. Thinking/Inquiry and Problem Solving might be assessed here.

 

Activity 3.4:  Applications: Finding the Amount and the

Present Value of a Long Term Investment

Time:  75 minutes

Description

Students extend their knowledge of compound interest and present value in order to make informed decisions about investments. Students learn to use the Financial Applications feature on a graphing calculator as well as the spreadsheet capabilities of software programs.

Strand(s) & Learning Expectations

Strand(s):  Financial Applications of Sequences and Series

Overall Expectations

FAV.02 - solve problems involving compound interest and annuities;

FAV.03 - solve problems involving financial decision making, using spreadsheets or other appropriate technology.

Specific Expectations

FA2.02 - solve problems involving compound interest and present value;

FA3.01 - analyse the effects of changing the conditions in long-term savings plans;

FA3.02 - describe the manner in which interest is calculated on a mortgage (i.e., compounded semi-annually but calculated monthly) and compare this with the method of interest compounded monthly and calculated monthly.

Prior Knowledge & Skills

Understanding of the compound interest formula

Planning Notes

·         Students need access to a graphing calculator or spreadsheet software.

·         Prepare a reference sheet that can be distributed to the students outlining keystrokes on the graphing calculator.

·         In the example provided, the steps required on a TI-83+ graphing calculator are outlined. If other technology is used, the instructions will require adjustment.

Teaching/Learning Strategies

Students require the use of a graphing calculator to complete this activity as it is written. Teachers may wish to lead the students using the overhead calculator, if one is available, so that the students can see the screen that they should have on their own calculator.

Student Activity

In the previous activity you calculated the amount that Carolyn would accumulate if $1000 was deposited for 4 years at 4%/a compounded annually. In this activity you will learn how to use the “Finance” feature of the TI83+ graphing calculator to evaluate this amount and investigate other related problems.

1.   Press [MODE], cursor down to FLOAT 0, 1, 2, etc. Select [2]. The calculator will now automatically round all values to two decimal places. All values will be rounded to the nearest cent.

2.   Press [APPS], [ENTER] to select Finance, [ENTER] to select TVM Solver. On the screen you should see

N= (number of interest payments)

I%= (annual interest rate)

PV= (present value of the investment or loan)

PMT= (periodic payment)

FV= (future value of the investment or loan)

P/Y= (payments per year)

C/Y= (compound periods per year)

PMT: END  BEGIN

Press 4 [ENTER] to store 4 years. Press 4 [ENTER] to store 4%. Press –1000 [ENTER] to indicate a cash outflow of $1000. Press 0 [ENTER] to show a payment of 0 (Periodic payments will be considered in future sections. In this activity this value will always be 0.)  Press 0 [ENTER] to show a future value of 0. Press 1 [ENTER] to show 1 payment per year. Press 1 [ENTER] to show 1 compound period per year. Select PMT: END. This indicates the payments are due at the end of each period. Cursor up to FV. Press [ALPHA] [Solve]. The value of the investment at the end of 4 years will appear.

3.   Carolyn discovers she can invest the $1000 at 4%/a compounded semi-annually. Adjust the values to calculate how much she will have at the end of 4 years if she chooses this option.

Cursor to N=. Press 8 [ENTER] to indicate 8 interest payments. Cursor to FV=. Press 0 [ENTER]. Cursor to P/Y=. Press 2 [ENTER] to indicate 2 payments per year. Cursor to C/Y=. Press 2 [ENTER] to indicate 2 compound period per year. Cursor to FV=. Press [ALPHA] [Solve]. The value of the investment after 4 years will appear.

4.   Find the amount that will accumulate if Carolyn finds an investment with interest at 4%/a compounded monthly.

Compare the following investments.

$8000 is invested at 5.25%/a compounded semi-annually for 5 years.

$8000 is invested at 5%/a compounded monthly for 5 years.

Which is the better investment? Why?

5.   Carolyn will need about $15 000 for her first year of university. (This includes tuition, books, residence and spending money.)  How much would she have to invest now at 4%/a compounded monthly to ensure she has enough 4 years from now?

Go to the Financial Applications program on the TI-83+ graphing calculator. Enter the following: N=48, I=4%, PV=0, PMT=0, FV=15000, P/Y=12, C/Y=12. Cursor to PV and press [ALPHA] [Solve]. Explain what each of the values entered means.

Follow up Questions

Provide the students with opportunities to practise skills with the finance program on the calculator. There will be many examples available in the students’ text. Students should be encouraged to check their results (for a few examples) by using the compound interest formula.

Assessment & Evaluation of Student Achievement

The focus of assessment should be on the consolidation of skills needed in problem solving. Students should be able to solve problems with and without the use of technology. Unless the teacher specifically requests the use of the formula, either type of solution should be acceptable.

Resources

TI-83+ Graphing Calculator Guidebook, Chapter 14 – Applications, Section 14-4

 

Activity 3.5:  Introduction to Geometric Series

Time:  75 minutes

Description

Students investigate a geometric series using an activity requiring financial decision making. The formula for the sum of a geometric series is developed.

Strand(s) & Learning Expectations

Strand(s):  Financial Applications of Sequences and Series

Overall Expectations

FAV.01 - solve problems involving arithmetic and geometric sequences and series.

Specific Expectations

FA1.05 - determine the sum of the terms of an arithmetic or a geometric series, using appropriate formulas and techniques.

Prior Knowledge & Skills

General term of a geometric sequence

Planning Notes

Access to a graphing calculator is helpful, but not essential.

Teaching/Learning Strategies

Make an overhead that states the problem only. Have the students investigate the problem. The students could make a table of values for each situation and use a graphing calculator to find an equation that models the total amount he is paid. Before completing the activity, discuss the fact that the amounts Sasha receives each day, in the second scenario, are the terms of a geometric series.

Student Activity

Sasha’s neighbours are planning on taking a vacation for two weeks (14 days). They have asked him to look after their cat and to water their plants. The neighbours have offered to pay him $5 per day or $0.01 the first day, $0.02 the second day, $0.04 the third day, $0.08 the fourth day, etc. Which method of payment should Sasha choose?

1.   Sasha notices that the amounts he will earn each day if he chooses the second plan are the terms of the geometric sequence
      0.01, 0.01(2)2,  0.01(2)3,…,0.01(2)13

He uses the following method to calculate the amount that he will have at the end of two weeks.
            S14 = 0.01 + 0.01(2) + 0.01(2)2 + 0.01(2)3 + … + 0.01(2)13

                        2S14 =            0.01(2) + 0.01(2)2 + 0.01(2)3 + … + 0.01(2)13 + 0.01(2)14

      2S14 – S14 = 0.01(2)14 – 0.01

                        S14 =

                        = $163.83

2.   Use this method to develop a formula to find the amount that Sasha will earn if he works any number of days.

3.   If the neighbours are away for 7 days which method of payment should Sasha choose?

4.   The sum of the terms of a geometric sequence is called a geometric series. Any geometric series can be written using the following form  Sn = a + ar + ar2 + ar3 … + arn-1

 

Use the method that Sasha used to develop the formula for the sum of the terms of a geometric series.

Teacher Facilitation

Ensure that the students have developed the correct formula for the sum of the geometric series. Assign additional questions using the formula. Make sure that some of the questions are related to financial applications.

Follow up Questions

1.   Find the amount that Sasha would earn if his neighbours were away for a month. Discuss whether this method of payment is reasonable.

2.   Write the geometric series using summation notation.

Assessment & Evaluation of Student Achievement

A short quiz could be used to assess knowledge and understanding of expectations related to geometric sequences and series. Communication could be assessed using question 1 from the activity.

Accommodations

Hand outs should be provided for students who have difficulty reading off of the overhead

 

Activity 3.6:  Applications: Finding the Amount and Present Value of an Annuity

Time:  150 minutes

Description

Using the example of a student who is saving money earned from a paper route, students investigate the amount of an annuity to determine interest, number of payments and the total amount. In the second part of the activity students calculate the present value of an annuity given the scenario of a hockey player who would like to set up a scholarship fund.

Strand(s) & Learning Expectations

Strand(s):  Financial Applications of Sequences and Series

Overall Expectations

FAV.02 - solve problems involving compound interest and annuities;

FAV.03 - solve problems involving financial decision making using spreadsheets or other appropriate technology.

Specific Expectations

FA2.02 - solve problems involving compound interest and present value;

FA2.03 - solve problems involving the amount and the present value of an ordinary annuity;

FA3.05 - communicate the solutions to problems and the findings of investigations with clarity and justification.

Prior Knowledge & Skills

·         Working knowledge of geometric series

·         Solving equations

Planning Notes

·         Students will need access to a graphing calculator and/or spreadsheet software.

·         Before beginning the activity discuss situations where students encounter periodic payments, both in light of amount accumulated and the amount needed to accumulate a specified sum (for example savings plans, scholarship funds, car loans)

·         Students need to be shown how to set up the first line diagram. Terms of the series should be left in unsimplified form (i.e., ).

Teaching/Learning Strategies

The night before the activity students could be directed to investigate in the media any situations where periodic payments are used. This could be used to initiate discussion before the student activity begins.

Student Activity 3.6.1:  How Much Do We Have?

Time:  75 minutes

Part A

Jeremy is in Grade 8. He has a paper route and wants to save for his college education. He determines that he has $100 per month to put into an account at 6%/a compounded monthly. How much will he have at the end of five years for his college education?

1.   Set up a line diagram showing the amount paid each month and the amount accumulated for each payment at the end of the time period.

2.   Show that the amounts form a geometric series.

3.   Calculate the sum of this geometric series using

Part B

Based on an average cost per year to attend a university or college of your choice, how much should be invested each month to obtain the goal of that amount? Assume 6%/a compounded monthly for 5 years.

Teacher Facilitation

Part A: Make sure the students’ line diagrams show several payments and the value of these payments at the end of the annuity. This will be important for the next activity when the amount invested at the end of each interval will not be known. The generality of determining amounts using the  formula is important.

Part B: If the students have not had the time to investigate actual amounts, suggest they use $10 000 per year. The teacher might suggest looking at other scenarios. For example, the student may be able to obtain a better interest rate.

Follow-up Questions

1.   Ask if the amount accumulated for Jeremy’s college education is realistic. Investigate the costs of going to university or college for one year at various educational institutions.

2.   Have the students fill in a table such as the following.

Amount

Payment

Number of Payments

Conversion Period

Interest Rate pa

?

$300

20

Semi-annually

8%

?

$500

24

Quarterly

12%

?

$100

36

Monthly

12%

?

$4000

10

Annually

8%

$10 000

?

40

Semi-annually

8%

$3000

?

24

Quarterly

12%

$5000

?

18

Monthly

12%

$12 000

?

15

Annually

6%

 

Student Activity 3.6.2:  How Much Do We Need?

Time:  75 minutes

A retired hockey star wants to set up a scholarship fund to assist an underprivileged child who would like to go to a post-secondary institution. He wants to ensure that the student will have $6000 per year for five years. How much should he give to the institution, now, to ensure that this can happen, if the institution is able to invest the money at 10%/a compounded annually.

1.   Set up a line diagram showing the present value of each of the $6000 payments.

2.   Explain why the amounts form a geometric series.

3.   Calculate the sum of the geometric series using the formula

Teacher Facilitation

Remind the students that they will need to find the present value of an amount when calculating the present value of each $6000 payment.

Follow-up Questions

Set up a table similar to the one in Activity 3.6.1 to find the present value of an annuity given the same kind of conditions illustrated in the table. Students should also complete questions that involve knowing the present value of the annuity and find the periodic payment.

Assessment & Evaluation of Student Achievement

Student work could be collected and assessed using an inquiry rubric. Students’ solutions should be organized and written using proper mathematical form. This is especially important when setting up the line diagram. Teachers could informally (or formally) assess progress and provide feedback to students to assist them to improve their communication skills.

 

Activity 3.7:  What Happens When?: Changing the Time, Rate and Amount

Time:  150 minutes

Description

Students will solve problems involving periodic payments. They will investigate the results of changing different parameters.

Strand(s) & Learning Expectations

Strand(s):  Financial Applications of Sequences and Series

Overall Expectations

FAV.03 - solve problems involving financial decision making using spreadsheets or other appropriate technology.

Specific Expectations

FA3.01 - analyse the effects of changing the conditions in long-term savings plans;

FA3.05 - communicate the solutions to problems and the findings of investigations with clarity and justification.

Prior Knowledge & Skills

·         Formula for the sum of a geometric series

·         Solve a quadratic equation

Planning Notes

Students will require access to a graphing calculator or spreadsheet software.

Teaching/Learning Strategies

Due to the number of parameters involved in these problems, it would be appropriate to complete a number of examples with the students. It may be helpful to use the overhead view screen projector with the graphing calculator, if it is available. The intent of this activity is to provide the students with an efficient method of investigating the result of changing some of the conditions when investing or borrowing. Students should be aware of the mathematics involved from the previous activity, but should make use of available technology to perform the calculations.

Student Activity

Example 1

Grant and Kera are both 75 years old. Kera is very money conscious. She was 20 years old when she began investing $1000 a year into an RRSP paying an average of 6%/a compounded annually. Grant, on the other hand, did not start to invest until age 50. He made an annual deposit of $3000 beginning at
age 50. The average interest rate he received on his investment was 8%/a compounded annually. What amount does each have today? What should Grant have invested each year in order to have the same amount as Kera at age 75? If Grant could only afford to invest $3000 per month, what average rate of interest would result in his saving the same amount as Kera?

Solution

To find the amount that Grant has, use the TI-83+ graphing calculator. Select [APPS], [1],[1] to choose the financial applications.

Enter the following

N=25, I=8%, PV=0, PMT=-3000 (this indicates a cash outflow of $3000 per year), FV=0, P/Y=1, C/Y=1, Select PMT:END. Cursor to FV, then push [ALPHA], [solve].

Now try the rest of the problem using the calculator.

Example 2

Stacey buys a $1000 RRSP today. After one year she adds $2500. By the end of the second year, the money has grown to $3851 as it has earned interest over time. What rate of interest does the money earn?

1.   Apply the compound interest formula to both the $1000 and $2500 investments. Assume that interest is compounded annually at the rate, i, to grow to $3851 to get

1000(1 + i)2 + 2500(1 + i) = 3851

2.   If this equation is written 1000x2 + 2500x – 3851 = 0, what does x represent.

3.   Use the quadratic formula and your calculator to solve for x and i.

4.   There are two solutions to the quadratic equation. Which one would you choose? Why?

Teacher Facilitation

There are many types of variables that can be adjusted in problems related to finance. Teachers should spend time discussing other scenarios and assign similar problems from other resources. In example 2, the interest rate for both investments is compounded annually, consider what will happen if the interest rate were compounded more frequently for one of the two.

Follow up Questions

1.   Maria received $50 on her 16th birthday, and $70 on her 17th birthday, both of which she immediately invested in the bank with interest compounded annually. On her 18th birthday, she had $134.97 in her account. Draw a time line and calculate the annual interest rate.

2.   Raul’s grandparents invested $1000 in a GIC for him on his 15th birthday and $2000 on his sixteenth birthday. During each of the two years the money earned 8.5% compounded annually.

a)   Draw a time line to show the situation.

b)   How much was in the fund on his 17th birthday?

Assessment & Evaluation of Student Achievement

Provide the students with two or three problems. Student ability to read, interpret, and solve the problems could be assessed. The students might be asked to hand in their solutions. Since a range of performances is likely, a rubric could be used to assess Application to Problem Solving and Communication.

Resources

TI-83+ Graphing Calculator Guidebook – Chapter 14.

 

Activity 3.8:  Mortgages: How They Work

Time:  150 minutes

Description

In this activity students will investigate various scenarios related to mortgages. They will compare methods of interest calculation, generate amortization tables for mortgages and analyse the effects of changing conditions of a mortgage.

Strand(s) & Learning Expectations

Strand(s):  Financial Applications of Sequences and Series

Overall Expectations

FAV.03 - solve problems involving financial decision making, using spreadsheets or other appropriate technology.

Specific Expectations

FA3.02 - describe the manner in which interest is calculated on a mortgage (i.e., compounded semi-annually but calculated monthly) and compare this with the method of interest compounded monthly and calculated monthly;

FA3.03 - generate amortization tables for mortgages, using spreadsheets or other appropriate software;

FA3.04 - analyse the effects of changing the conditions of a mortgage (e.g., the effect on the length of time needed to pay off the mortgage of changing the payment frequency or the interest rate);

FA3.05 - communicate the solutions to problems and the findings of investigations with clarity and justification.

Prior Knowledge & Skills

Students should have acquired an understanding of annuities.

Planning Notes

Access to the TI-83+ calculators is required. If different technology is used, the instructions in this activity will have to be modified.

Teaching/Learning Strategies

Students could be asked to visit a local financial institution to determine the method of interest calculation on loans and mortgages. An alternative would be to invite a guest speaker from a local financial institution to discuss these issues with the class. Before beginning this activity, teachers should introduce students to some of the language associated with mortgages. It is important for students to be comfortable using the financial applications of a graphing calculator or spreadsheet software. Teachers may choose to have the students use a computer spreadsheet to generate the amortization schedules.

Student Activity

Mortgages are a special type of annuity. They are also a fact of life for most Canadian families. When applying for a mortgage through a financial institution, it is important to know how much your family can afford to pay on a monthly basis, the term of the amortization, and the interest rate charged by the financial institution. The TI-83+ calculator has a software package that will help determine the value of some of these parameters.

Ron and Lynda are purchasing a new home. They will need to borrow $90 000 for the home. The amortization period, which best fits their financial situation is 25 years. Discuss why this might be so. The current interest rate is 8.7%/a. Interest is compounded semi-annually and calculated monthly. The couple wants to know how much it will cost them each month to pay off the loan. Assume that they will make one payment per month.

To solve this problem, select [APPS], [1], [1] (this selects the TVM solver). Enter, N=25x12, I=8.7, PV=90 000, PMT=0, FV=0, P/Y=12, C/Y=2, select PMT:END. Cursor to PMT, press [ALPHA], [solve]. This finds the payment of $727.52. (It will appear as a negative because this is a cash outflow.)

1.   Create a schedule of payments for the first 5 years of the mortgage. Include a graph showing the declining balance at the end of each year.

2.   After 5 years, the interest rate is reduced to 6.7%/a compounded semi-annually and calculated monthly. Find the amount of the monthly payments. (Remember that the new present value will be the amount owing at the end of the first five-year period.)

3.   Create a new schedule of payments for 5 years.

Teacher Facilitation

Teachers may wish to prepare a handout, which covers the menu and the steps required to compute the amortization schedule on the TI-83+ calculator.

Assessment & Evaluation of Student Achievement

Learning skills and the ability to read and interpret problems might be informally assessed. Students could be asked to write a report on information obtained from visiting financial institutions or from listening to a guest speaker. This report could be assessed for Communication skills. The amortization tables could be handed in and assessed for Application and Knowledge/Understanding.

 

Activity 3.9:  Financial Decision Making: A Case Study

Time:  300 minutes

Description

Students are presented with a realistic situation involving financial decision making. They analyse the situation and suggest financial decisions to be made. Students are required to write a report justifying their decisions using the mathematics learned in this unit.

Strand(s) & Learning Expectations

Strand(s):  Financial Applications of Sequences and Series

Overall Expectations

FAV.01 - solve problems involving arithmetic and geometric sequences and series;

FAV.02 - solve problems involving compound interest and annuities;

FAV.03 - solve problems involving financial decision making, using spreadsheets or other appropriate technology.

Specific Expectations

It is expected that as many specific expectations as possible in the Financial Applications of Sequences and Series strand will be addressed in this summative assessment activity.

Planning Notes

Teachers may choose to review some of the major concepts discussed in the previous activities (e.g., computation of interest, annuities).

Teaching/Learning Strategies

Conduct a group discussion to enable students to generate an expense report for a typical month in the life of a family of four (two adults, two children in elementary school). Include in the report all expenses related to the management of a home. Emphasize in the student activity that a full and detailed report on the Johnston financial situation must be made, including calculations, all expenses and rationale. Communication skills should be emphasized.

Student Activity

Part 1

The Johnstons are married with two children, Josh, age 13 and Judy, age10. They have a 25-year mortgage of $75 000 at 8%/a compounded semi-annually and calculated monthly; a car loan of $18 000 taken out for five years at 10%/a compounded monthly. They also have the normal expenses of running a house (e.g., utilities, taxes, groceries, etc.). The Johnstons have a single income of $45000 per year and are contemplating having both parents return to work now that the children are both in school. Analyse the Johnstons’ financial situation and decide if this is necessary. Justify your answers.

After 5 years, the mortgage must be renewed with an interest rate of 8.5%/a compounded semi-annually and calculated monthly. How will this effect their monthly expenses?

Part 2

Write a short report about long-term financial and educational planning. What have you learned? How has this information changed the way you view a mortgage? How could this influence your financial choices? You may wish to comment on the feelings that other people might have, or what they might know or not know about this matter. You may want to describe your own personal long-term plans in this area.

Assessment & Evaluation of Student Achievement

All categories of the Achievement Chart should be assessed in this summative assessment activity. Since a range of performances is likely, a rubric might be used. Teachers might choose to use a pencil-and-paper test to assess Knowledge/Understanding of expectations in the unit that are not specifically addressed in this activity.

Suggested Rubric to be used with Activity 3.9

Categories

Level 1
(50-59%)

Level 2
(60-69%)

Level 3
(70-79%)

Level 4
(80-100%)

Thinking/Inquiry and Problem Solving

- analyses the effects of changing variables in financial applications

- takes into account only a limited number of factors in analysing the problem

 

- is unable to devise a reasonable financial plan

- takes into account some of the factors in analysing the problem

 

 

- offers a solution which is somewhat justified by the facts given

- takes into account most of the factors in analysing the problem

 

 

- makes a reasonable suggestion based on the facts given

- takes into account all, or almost all, of the factors in analysing the problem

 

- identifies more than one option based on the facts given

Communication

- communicates with clarity and justification

- communicates with limited clarity and limited justification

- communicates with some clarity and some justification

- communicates with general clarity and justification

- communicates with a high degree of clarity and justification

Note: A student whose achievement is below level 1 (50%) has not met the expectations for this assignment of activity

Accommodations

Allow extra time for those students who need it.

Resources

Banks and trust companies

The personal financial planner at a local financial institution

 

 

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