A sum of money at compound interest doubles in 12 years. In how many years will it become 64 times? MCQ with Answer and Explanation

A sum of money at compound interest doubles in 12 years. In how many years will it become 64 times?
A. 84 years
B. 48 years
C. 72 years
D. 60 years
Answer: Option C
Solution (By JKSSB Mock Tests)
64 = 2⁶, so 12 × 6 = 72 years.

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Practice More Compound Interest Questions

Question #1
The compound interest on a certain sum of money for 2 years at 10% per annum is Rs. 441. What would be the simple interest on the same sum at the same rate for the same time?
A. Rs. 410
B. Rs. 435
C. Rs. 420
D. Rs. 430

Correct Answer: Option C


Explanation:
Effective rate of compound interest for 2 years at 10% = 10 + 10 + (1010)/100 = 21%. Simple interest rate = 10 * 2 = 20%. Given 21% of sum = 441 => 1% of sum = 21. Simple Interest = 20% of sum = 20 * 21 = Rs. 420.

This question belongs to: Maths Compound Interest
Question #2
The present population of a town is 44100. If it increases at 5% per annum, what was the population 2 years ago?
A. 43000
B. 41000
C. 42000
D. 40000

Correct Answer: Option D


Explanation:
Population 2 years ago = 44100 / (1.05)² = 44100 / 1.1025 = 40000.

This question belongs to: Maths Compound Interest
Question #3
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?
A. 42 years
B. 28 years
C. 35 years
D. 21 years

Correct Answer: Option B


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

This question belongs to: Maths Compound Interest