A sum of money becomes 2 times in 4 years at compound interest. In how many years will it become 8 times? MCQ with Answer and Explanation

Explanation:
Difference for 3 years = P * (R/100)^2 * (3 + R/100) => 244 = P * (5/100)^2 * (3 + 5/100) => 244 = P * (1/400) * (3.05) => P = (244 * 400) / 3.05 = 97600 / 3.05 = Rs. 32000.

Explanation:
20000(1+r)² = 22050 ⇒ (1+r)² = 1.1025 = (1.05)² ⇒ r = 5%.

Explanation:
The sum becomes 2^1 times in 7 years. It will become 16 (2^4) times in 4 * 7 = 28 years.