Question

Calculate the annual simple interest rate as a percent. A sum of money will be tripled in 25 years at the rate of __% per annum.

Answer 1

Explanation:

Let x be the principal amount.

Simple Interest Formula:

`a = p(1 + rt)`

where a = final amount

p = principal amount

r = annual interest rate

t = time taken in years.

given a = 3x, p = x, t = 25, substitute a,p and t into formula.

`3x = x(1 + 25r) \\ 1 + 25r = 3 \\ 25r = 3 - 1 \\ 25r = 2 \\ r = 2 / 25 \\ = 0.08 \\ = (0.08 * 100)percent \\ = 8percent`

8%*