Question

A sum of money doubles itself in 4 years at a
certain rate of interest. In how many years will it
treble itself at the same rate of interest?

please tell me with the method​

Answer 1

Answer: 8 Years

Explanation:

The sum of money doubles in 4 years means the interest for 4 years equals to original sum of money I.e. Principle. Let the Principle = P and rate of interest = r %

So, P + P * r *4/100 = 2P

Or, p*r*4/100 = 2P - P = P

Or, r = 100/4 = 25 %

For sum to be treble, the interest should be twice the Principle I.e. P * (25/100) * t = 2P where t is the period when the sum will be 3 times

Or, t = 100 * 2/25 = 8 years

Simply you can also give a statement that when sum is doubled in 4 years for simple interest, the sum will be tripled in 4 × 2 = 8 years

HOPE THIS MAY HELP YOU!!!