12.03 Simple interest
If \$16\,716 of simple interest was earned in 7 years, find how much interest was earned:
Each year
Each month
Assuming that a year has 365 days and 52 weeks, calculate the simple interest earned on the following investments:
\$2540 at 9\% p.a. for 2 years.
\$2010 at a rate of 6\% p.a. for 13 months.
\$1050 at a semiannual rate of 1.1\% for 9 years.
\$7000 at 1.8\% per quarter for 9 years.
\$5320 at 6\% p.a. for 95 weeks.
\$5440 at 6\% p.a. for 566 days.
Assuming that a year has 365 days and 52 weeks, calculate the simple interest charged on the following loans:
\$8000 at 8\% p.a. for 6 years.
\$3860 at a rate of 9\% p.a. for 13 months.
\$5240 at 4\% p.a. for 73 weeks.
\$5010 at 5\% p.a. for 666 days.
Bianca takes out a loan of \$800 to pay for an online course. Simple interest is calculated at 9\% per year, charged monthly. If she repays the loan in 9 months, how much interest does she pay in total?
The graph shows the amount of simple interest charged each year by a particular bank, on a 3-year loan:
Find the total amount of simple interest charged on a loan of \$5000.
Calculate the simple interest rate per annum, r, charged by the bank on 3-year loans.
Dave and Emily are looking to invest \$11\,600 and \$18\,300 respectively for 6 years. The table shows the simple interest rates for different principals:
Calculate the interest Dave will earn on his investment.
Calculate the interest Emily will earn on her investment.
| Principal | Rate p.a. |
|---|---|
| \text{Between \$4\,800 and \$14\,800} | 4\% |
| \text{Between \$14\,800 and \$24\,800} | 5\% |
| \text{Greater than \$24\,800} | 6\% |
How much will they earn if they combine their principals and invest together?
Should they invest separately or together? Explain your answer.
Luke's investment of \$3000 earned simple interest of 4\% p.a. for the first 8 years, and 2\% p.a. for the next 5 years.
Calculate the total amount of interest earned.
Calculate the final value of these investments:
\$6170 at 5\% p.a. for 6 years.
\$9060 at 4\% p.a. for 44 months.
\$4230 at 8\% p.a. for 32 weeks.
\$4620 at 6\% p.a. for 146 days.
\$402 is invested at 4\% p.a. simple interest for 9 years. After this time the principal plus interest is reinvested at 6\% p.a. simple interest for 8 more years.
Calculate the value of the investment after 9 years.
Calculate the final value of the investment.
Calculate the total amount of interest earned.
The simple interest earned on each investment is given below. Find the annual interest rate r, as a percentage, correct to one decimal place:
\$3600 over 2 years is \$504.00.
\$1600 over 3 quarters is \$103.20
\$4800 over 20 months is \$760.00
\$7550 over 9 years is \$6523.20.
\$5800 over 6 quarters is \$321.90 .
\$5500 over 24 months is \$385.00.
Find the principal that earned:
\$865 simple interest, at 3\% p.a. over 6 years.
\$390 simple interest, at 2.5\% p.a. over 4 years.
\$1200 simple interest, at 1\% per month over 2 years.
\$3260 simple interest, at 2.5\% per week over 6 months.
Sally made loan repayments totalling to \$4320 on a loan of \$4000 over 4 years.
Calculate the total simple interest charged on the loan.
Calculate r, the annual simple interest rate.
For his investment into government bonds , Buzz was paid simple interest of 9\% p.a. Calculate the size of Buzz's initial investment \$P, if he earned \$294.12 interest after 2 years.
If \$2196 is invested at 2\% p.a. simple interest for 8 years, what simple interest rate r, would earn the same amount of interest in only 5 years?
Express r as a percentage, correct to two decimal places.
\$552 is invested at a simple interest rate of 5\% p.a.
Calculate the interest that will be earned on the investment in one year.
Calculate the number of years it will take the investment to grow to \$828.
\$1957 is invested at a simple interest rate of 6\% p.a. Calculate the number of years needed for interest of \$1174.20 to be earned on the investment.
\$2379.00 is invested at a simple interest rate of 2\% p.a. Calculate the number of quarters needed for interest of \$23.79 to be earned on the investment.
\$63\,790 is invested at a simple interest rate of 8\% p.a. Calculate the number of months needed for interest of \$7654.80 to be earned on the investment. Round your answer to the nearest month.
\$7050 is invested at a simple interest rate of 7\% p.a. Calculate the number of years needed for it to grow to \$7950. Round your answer to two decimal places.