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A sum of money placed at compound interest doubles itself in 5 years. It will amount to eight times itself in

A) 10 years
B) 12 years
C) 15 years
D) 20 years

Correct Answer:



C) 15 years

Description for Correct answer:

\( \Large P \left(1 + \frac{R}{100}\right)^{5} = 2P \)

= \( \Large \left(1 + \frac{R}{100}\right)^{5} = 2 \)

Let \( \Large P \left(1 + \frac{R}{100}\right)^{n} = 8P \)

\( \Large \left(1 + \frac{R}{100}\right)^{n} = 8 = 2^{3} \)

Fropm equation (i)

\( \Large \left(1+\frac{R}{100}\right)^{n} = { \left(1+\frac{R}{100}\right)^{5} }^{3} = \left(1+\frac{R}{100}\right)^{15} \)

Therefore, n = 15 years

Part of solved Simple and compound interest questions and answers : >> Aptitude >> Simple and compound interest

Comments

Similar Questions

1). The number of years for an amount of money to triple at 16% simple interest is

A). \( \Large 12\frac{1}{2} \)

B). 10 years

C). \( \Large 8\frac{1}{2} \) years

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A). 3%

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C). 5%

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C). 216 : 125

D). 125 : 216

5). At what rate percent per annum calculated in simple interest will a sum of money double in 10 years?

A). 10%

B). 12%

C). 12.50%

D). 13.50%

6). An amount at compound interest doubles itself in 4 years. In how many years will the amount becomes 8 times itself?

A). 8 Years

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7). A man invested Rs.1000 on a simple interest at a certain rate and Rs.1500 at 2% higher rate. The total interest in three years is Rs.390. What is the rate of interest for Rs.1500?

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8). A sum amounts to Rs. 1352 in 2 yr at 4% compound interest. The sum is

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9). What will be the present worth of RS. 169 due in 2 yr at 4% pa compound interest?

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10). What amount will be received on a sum 0f Rs. 1750 in 2 1/2 Yr, if the interest is compounded at the rate of 8% pa?

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