• Simple interest calculations are used to find the approximate interest gained once money is invested. It is assumed in each case that the interest rate remains constant.
• I = P × R × T / 100 = PRT / 100

where :

1. Find the simple interest when £ 200 is invested for 1 1/2 years at an interest rate of 9.5 % p.a. (p.a. means per annum, or per year).

   I = PRT / 100 = £200 × 9.5 × 1.5 / 100 = £ 28.50

2. Approximately how long would it take for £ 300 to produce £ 40 simple interest at a rate of 8.25 % p.a.?

   In this problem we have P = £ 300, I = £ 40, R = 8.25 %

   I = PRT / 100 , so £40 = £ 300 × 8.25 × T / 100 = £ 28.50

   = 24.75 × T (as £300 × 8.25 / 100 = £ 24.75)

   so T = £40 / £24.75 = 1.61 years (Divide both sides of the equation by the same amount of 24.75).

   0.61 years is 0.61 × 12 months

   = 1 year 7 months, rounded to the nearest month

The interest in this exercise is simple interest.

1. Find the interest when £650 is invested for 6 years at 12% p.a.
2. Find the interest when £200 is invested for 3 1/2 years at 9% p.a.
3. Find the interest when £265 is invested for 6 months at 9% p.a.
4. Find the interest when £600 is invested for 4 1/2 years at 8 1/4% p.a.
5. Find the interest when £150 is invested for 4 years at 12 1/2% p.a.

6. What amount of money has been invested when it takes 4 1/2 years for an amount of £105 interest to be earned, at a rate of interest of 14% p.a.?
7. Find the interest when £350 is invested for 5 years at 7% p.a.
8. Find the interest when £12750 is invested for 1 year at 8% p.a.
9. Find the interest when £750 is invested for 8 1/2 years at 3 1/2% p.a.
10. Find the interest when £5643 is invested for 9 years at 2% p.a.

• Please type your answers into the corresponding spaces below.
• Please answer to two decimal places.