Question

A certain sum amounts to rs. 798.60 after three years and 878.46 after four years at compound interest. find the rate and the sum

Answer 1

Answer:

Explanation: Hope this will help you!

Sum of 3rd year=?

Amount at the end of 3rd year=798.60Rs

Sum of 4th year=Amount of 3rd year

Amount of 4th year=878.46Rs

To find @ of interest:-

In 4th year-

A=p(1+r/100)^n

878.46=798.60(1+r/100)

(1+r/100)=878.46/798.60

1+r/100=14641/13310

r/100=14641/13310-1

r/100=1331/13310

r=1331/13310*100

r=1*10

r=10%

Hence @ of interest is 10%p.a.

To find Sum in 3rd year-

A=P(1+r/100)

798.60=P(1+10/100)

P=11/10*79860/100

P=1.1*798.6

P=878.46 Rs

Sum =878.46 Rs

Hope this will help you