A sum of money invested at compound interest doubles itself in 19 years. In how many years will it become 4 times of itself? MCQ with Answer and Explanation

A sum of money invested at compound interest doubles itself in 19 years. In how many years will it become 4 times of itself?

A. 58 years

B. 48 years

C. 28 years

D. 38 years

Answer: Option D

The sum doubles (2^1) in 19 years. It will become 4 (2^2) times in 2 * 19 = 38 years.

This question belongs to: Maths Compound Interest

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Question #1 Report Error

The compound interest on Rs. 1700 at 10% per annum for 2 years is:

A. Rs. 357

B. Rs. 391

C. Rs. 374

D. Rs. 340

Correct Answer: Option A

Explanation:
A = 1700 × 1.21 = 2057, CI = 2057 − 1700 = Rs. 357.

This question belongs to: Maths Compound Interest

Question #2 Report Error

A sum of money placed at compound interest becomes double of itself in 10 years. In how many years will it become 8 times of itself?

A. 50 years

B. 40 years

C. 20 years

D. 30 years

Correct Answer: Option D

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

This question belongs to: Maths Compound Interest

Question #3 Report Error

At what rate percent per annum will Rs. 10000 amount to Rs. 12100 in 2 years, compound interest compounded annually?

A. 12%

B. 8%

C. 10%

D. 14%

Correct Answer: Option C

Explanation:
Amount/Principal = 12100 / 10000 = (11 / 10)^2. Therefore, 1 + R/100 = 11/10 => R/100 = 1/10 => R = 10%.

This question belongs to: Maths Compound Interest