Question

At a certain sum of money at simple interest amounts to Rs . 690 in 3 years and to Rs . 750 in 5 years . Find the sum at the rate of 10 %​

Answer 1

let principle amount be P and rate R

S. I = (P*R*T)/100

when T = 3

S.I + P = 690

3PR/100 + P = 690.

5PR/100 + P = 750

subtracting we get

1st eqn * 5 - 2nd eqn *3

2P = 1200

P = 600

Sum at R= 10

Sum = SI + P = 6000T/100 + 600

= 600 + 60T