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5.03 Varying the frequency of compounding

Worksheet
Final value
1

A \$2400 investment earns interest at 4\% p.a. over 7 years.

a

Determine whether the following compounding periods would earn the greatest interest:

i

annually

ii

quarterly

iii

monthly

iv

weekly

b

Calculate the value of this investment if compounded quarterly.

2

Calculate the final value of each of the following investments:

a

A \$9560 investment earns interest at 4\% p.a. compounded monthly over 9 years.

b

A \$9640 investment earns interest at 4.7\% p.a. compounded weekly over 4 years.

c

A \$2000 investment earns interest at 2.2\% p.a. compounded daily over 16 years.

d

A \$5510 investment earns interest at 3.7\% p.a. compounded weekly over 6 years.

e

A \$7000 investment earns interest at 3.9\% p.a. compounded monthly over 13 years.

3

Calculate how much is owed at the end of the following loan periods:

a
Brad borrows \$8000 from a loan shark at a rate of 5.4\% p.a. compounded semi-annually, for 5 years.
b
Victoria borrows \$4000 from a loan shark at a rate of 2.8\% p.a. compounded quarterly, for 3 years.
c
\$6000 is borrowed from a bank at a rate of 7.2\% p.a. compounded weekly, for 5 years.
d
\$7000 is borrowed from a bank at a rate of 3.4\% p.a. compounded monthly, for 6 years.
e
\$2000 is borrowed from a bank at a rate of 1.3\% p.a. compounded daily, for 3 years. Assume there are 365 days in a year.
4

Emma wants to invest \$1400 at 5\% p.a for 5 years. She has two investment options, compounding quarterly or compounding monthly.

a

Calculate the value of the investment if it is compounded quarterly.

b

Calculate the value of the investment if it is compounded monthly.

c

Calculate how much extra the investment is worth if it is compounded monthly rather than quarterly.

5

Steph wants to invest \$2000 at 5\% p.a for 6 years. She has two investment options, compounding quarterly or compounding monthly, and wants to find the difference in the final investment values of these two options.

a

Calculate the value of the investment if it is compounded quarterly.

b

Calculate the value of the investment if it is compounded monthly.

c

Hence, calculate how much extra the investment is worth if it is compounded monthly rather than quarterly.

6

Maria has \$2000 to invest for 2 years and would like to know which investment plan to enter into given the following options:

  • Plan 1: invest at 5.18\% p.a. interest, compounded monthly

  • Plan 2: invest at 6.54\% p.a. interest, compounded quarterly

  • Plan 3: invest at 5.80\% p.a. interest, compounded annually

a

Calculate the future value of the investment under Plan 1.

b

Calculate the future value of the investment under Plan 2.

c

Calculate the future value of the investment under Plan 3.

d

Which investment plan yields the highest return?

Interest
7

For each investment below, calculate the total amount of interest earned:

a

Mae’s investment of \$4430 earns interest at 2.9\% p.a. compounded quarterly over 18 years.

b

Beth’s investment of \$7520 earns interest at 4.1\% p.a. compounded monthly over 20 years.

c

Mia’s investment of \$1040 earns interest at 4\% p.a. compounded weekly over 18 years.

d

Han’s investment of \$2470 earns interest at 2.6\% p.a. compounded semi-annually over 4 years.

8

Sean borrows \$7000 at a rate of 5.5\% p.a. compounded weekly. If she pays off the loan in a lump sum at the end of 5 years, find how much interest she pays. Assume there are 52 weeks in a year.

9

Pauline borrows \$50\,000 at a rate of 5.4\% per annum. If she pays off the loan in a lump sum at the end of 7 years, find how much interest she pays if the interest is compounded:

a

Daily

b

Monthly

c

Quarterly

10

Frank is working out the compound interest accumulated on his loan. He writes down the following working:

A = 6000\left(1+\dfrac{0.08}{4}\right)^{(7\times4)}

a

How much did he borrow in dollars?

b

What is the annual interest rate as a percentage?

c

Is the interest being compounded weekly, monthly, quarterly or annually?

d

For how many years is he accumulating interest?

e

How much interest does he pay?

11

A \$110\,000 investment earns interest at 4\% p.a. compounded semi-annually over 5 years. The compound interest table shows the future value of a \$1000 investment compounded at various interest rates and over a certain number of periods.

\text{Interest rate} \\ \text{per period}10\text{ years}20\text{ years}30\text{ years}40\text{ years}50\text{ years}
0.5\%1051.141104.901161.401220.791283.23
1\%1104.621220.191347.851488.861644.63
1.5\%1160.541346.861563.081814.022105.24
2\%1218.991485.951811.362208.042691.59
2.5\%1280.081638.622097.572685.063437.11

Using the table, calculate:

a

The future value of this investment.

b

The total amount of interest earned.

12

A bank offers the following rates on investment accounts:

  • Option 1: 4\% p.a. compounded annually

  • Option 2: 3.94\% p.a. compounded quarterly

The bank is looking to also offer a third option, compounding semi-annually. Comment on the rate they would need to offer so that a \$1000 investment results in the same returns across all three options.

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MS2-12-5

makes informed decisions about financial situations, including annuities and loan repayments

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