A sum of money at compound interest becomes 9 times in 2 years. In how many years will it become 81 times? MCQ with Answer and Explanation

Explanation:
Half-yearly rate = 10/2 = 5%. Time = 2 half-years. Amount = 30000 * (1 + 5/100)^2 = 30000 * 1.1225 = Rs. 33075. Compound Interest = 33075 - 30000 = Rs. 3075.

Explanation:
The sum becomes 2^1 times in 10 years. It will become 8 (2^3) times in 3 * 10 = 30 years.

Explanation:
100 = 10², so 2 × 2 = 4 years.