Question

At what rate percent per annum will a sum of money double itself in 8 years​

Answer 1

Step-by-step explanation:

Hint:- In 8 years money from Interest will be come equal to the principal

amount invested. So, money had been doubled in 8 years.

Let the initial amount of money invested will be Rs. x.

Then after 8 years money had become 2x.

Out of Rs. 2x, money from interest will be 2x – initial amount invested = 2x – x = x.

Let the rate of interest be r.

So, now we will use a simple interest formula.

According to Simple Interest (S.I) formula.

⇒S.I.=PRT100⇒S.I.=PRT100

. Where P is principal amount, R is rate of interest and T will be time period.

So, putting the values in the above formula. We will get,

⇒x=xr(8)100⇒x=xr(8)100

On solving the above equation. We will get,

⇒ r = 1008 = 12.5⇒ r = 1008 = 12.5