Question

In simple interest, a sum of money doubles itself in 10 years. In how many years it will get triple itself.

Answer 1

Let the Principal be P and Rate of interest be r % per annum. 

Here the number of years n = 10 years 

Given in 10 years P becomes 2 P. 

A = P + I

After 2 years A = 2P 

i.e. 2P = P + I 

2P – P = I

Now if the amount becomes triple then A = P + I 

= 3P 

3P = P + I 

3P – P = I 

2P = I

∴ After 20 years the amount get tripled.