Question

09. Find the rate A sum of money doubled itself in 15 years. In how many years will it become 8 times of itself?​

Answer 1

45 years

Explanation:

Let the sum be x and CI=2x

We know that

CI=P(1+100R)T

2x=x(1+100R) ^15

(1+100R)^15=2

Let m be the number of years.

Therefore,

x(1+100R)m=8x

(1+100R)m=23

(1+100R)m=[(1+100R)^15]3

From eqn(1)

(1+100R)m=(1+100R)45

On comparing both power, we get

m=45 years