Question

A certain sum of money amounted to rs. 1020 at 9% in a time in which rs. 720 amounted to rs. 880 at 4%. if the rate of interest is simple, find the sum.

Answer 1

Here final amount is given 1020 rupees at 9%, and

720 rupees amounted to 880 at 4%

First let us find the time for which 720 amounted to 880 rupees.

P+PNR/100 = 880

720(1+0.04N) = 880

0.04N = 160/720

N = 5.556 years

Now for the amount of 1020/- interest was 9% and time = 5.556 years

TO find P:

P(1+5.556*0.09) = 1020

P (1.50) = 1020

P =680 rs.

Hence the sum = 680 rs.