Question

If the ratio of principal and amount in current year at simple interest is 9:17 and after 27.5 more year the ratio will become 15:43.Find the rate of simple interest?

Answer 1

Answer:

Suppose after t years, P= Rs. 4x and Amount = Rs. 5x

⇒ P+ S.I. after t years = Rs. 5x .....(i)

Also, given P : [P+ S.I.] after (t+3) years=5:7=1:

5

7

=4x:

5

7

×4x=4x:

5

28x

⇒ P + S.I. after (t + 3) years = Rs

5

28x

.....(ii)

∴ Eq (i) - Eq (ii) gives

S.I. after 3 years = Rs (

5

28x

−5x)=Rs

5

3x

∴ Rate of interest =

4x×3

5

3x

×100

=5% p.a.