A sum of money invested at compound interest doubles itself in 5 years. In how many years will it become 8 times of itself? MCQ with Answer and Explanation

Explanation:
Difference for 3 years = P * (R/100)^2 * (3 + R/100) => 186 = P * (10/100)^2 * (3 + 10/100) => 186 = P * (1/100) * (3.1) => 186 = P * 0.031 => P = 186 / 0.031 = Rs. 6000.

Explanation:
The sum doubles (2^1) in 9 years. It will become 8 (2^3) times in 3 * 9 = 27 years.

Explanation:
Half-yearly rate 5%, n=3. A = 16000 × (1.05)³ = 16000 × 1.157625 = 18522, CI = 18522 − 16000 = 2522.