A sum of money placed at compound interest becomes double of itself in 7 years. In how many years will it become 16 times of itself? MCQ with Answer and Explanation

Explanation:
Difference for 2 years = P * (R/100)^2 => 65 = P * (10/100)^2 => 65 = P * 0.01 => P = 65 / 0.01 = Rs. 6500.

Explanation:
Quarterly rate = 12 / 4 = 3%. Time = 4 quarters. Amount = 50000 * (1 + 3/100)^4 = 50000 * (1.03)^4 = 50000 * 1.12550881 = Rs. 56275.44. Compound Interest = 56275.44 - 50000 = Rs. 6275.44.

Explanation:
128 = 2⁷, so 15 × 7 = 105 years.