Question

On a certain sum of money, lent out at C.I., interests for first, second and third years are Rs. 1,500; Rs.1,725 and Rs. 2,070 respectively.

Find the rate of interest for the

(i) second year

(ii) third year.

Answer 1

$I_2=I_1+\frac{R}{100\ast I_1}$
Here I_2 is second year interest and I_1 is first year interest
R=rate
So
$1725=1500+\frac{R}{100}\times 1500$
1725-1500=15R
$\frac{225}{15}=R$
Rate=15%
U can also use
$I_3=I_2+\frac{R}{100\ast I_2}$
$2070=1725+\frac{R}{100\ast 1725}$
Rate=20%