A sum of money amounts to Rs. 10648 in 3 years and Rs. 9680 in 2 years. The rate of interest is?

Let P be the principle and R% per annum be the rate. Then,
P(1 + R/100)³ = 10648 ....(i)
and P(1 + R/100)² = 9680 .....(ii)
on dividing (i) by (ii), we have
⇒ (1 + R/100) = 10648/9680
⇒ R/100 =968/9680 = 1/10
∴ R =100/10 = 10%