Question

a sum of money doubles in 20 years on simple interest .it will get triple at the same rate in

Answer 1

use the equation
A = P(1 + rt)

Answer 2

2P = P ( 1 + r*20)
solve for r

2 = 1 + r*20

1 = r*20

r = 1/20 = .05

Now plug r = .05 into the formula

A = P(1 + r*t) , and substitute r = .05, and t = 3 , A = 3P