A principal amount grows to Rs. 6690 in 3 years and Rs. 10,035 in 6 years under compound interest. What is the original principal?

Explanation

Let the principal be P and the rate of interest be R%. According to compound interest formula: P(1 + R/100)^3 = 6690 and P(1 + R/100)^6 = 10035. Dividing the second equation by the first gives (1 + R/100)^3 = 10035 / 6690 = 3/2. Using this, we find P = 6690 × (2/3) = Rs. 4460.