Discussion Forum



1)

A sum of money on compound interest amounts to Rs. 10,648 in 3 years and Rs. 9680 in 2 years. The rate of interest per annum is


A) 5%

B) 10%

C) 15%

D) 20%

E) 25%

Answer:

Option B

Explanation:

Let  Sum be $P$ and rate be $R\%$ per annum.

Then $P\left(1+\frac{R}{100}\right)^{2}$ $=9680$    ---------------------- (1)

$P\left(1+\frac{R}{100}\right)^{3}$ $=10648$   -----------------------------(2)

Divide equ. (2) by (1)

$\Rightarrow 1+\frac{R}{100}$ $=\frac{10648}{9680}$

$\frac{R}{100}$ $=\frac{1}{10}$ = 10%