Question

A sum of money doubles itself in 5 years. How much time will it taken for it to quadruple at the same rate of interest ?​

Answer 1

Answer:

If the money doubles in 5yesrs then interest is same as principal

Let principal be p, then interest = p

p = p×r×5/100

1 = r/20

r = 20%

Let T be time to quadruple

Then for principal p, interest = 3p

3p = p ×20 ×T/100

3 = T/5

T = 3×5 = 15 years