A sum of money amounts to rs.6690 after 3 years and to rs.10,035 after 6 years on compound interest. Find the sum.

Let the sum be rs.P.then

P(1+R/100)³=6690…(i) and   P(1+R/100)⁶=10035…(ii)

On dividing, we get (1+R/100)³=10025/6690=3/2.

Substituting this value in (i),we get:

P*3/2=6690 or P=(6690*2/3)=4460

Hence, the sum is rs.4460.