Compound Interest Practice Test 5

Question : 40 of 40

Marks: +1, -0

A sum of money placed at compound interest doubles itself in 10 years. In how many years will it amount to four times itself?

Solution:

Here,

2P=P(1+r/100)^10

∴(1+r/100)^10=2

...(i)
Now,

4P=P(1+r/100)^n

⇒(1+r/100)^n=2^2=(1+r/100)^20

[From equation (i)]
∴ n = 20 years

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