Question

7. A certain sum of money amounts to 756 in 2
years and to 873 in 3.5 years. Find the sum
and the rate of interest.​

Answer 1

Amount in 2 years = ₹756 ===> eqn 1

Amount in 3.5 years = ₹873 ===> eqn 2

Substract eqn 1 from eqn 2

Amount in 3.5 years - Amount in 2 years = Interest in 1.5 years

===> 873 - 756 = Interest in 1.5 years

Interest in 1.5 years = 117

Interest in 2 years = 117 / 1.5 × 2 ==> ₹ 156

Principal ( P ) = Amount - Interest

= 756 - 156

= ₹600

Simple Interest = PTR / 100

156 = 600 × 2 × R / 100

R = 156 × 100 / 600 × 2

R = 15600 / 1200

R = 13%

Rate of interest = 13%