In how much time will a sum of money double itself at 12.5% annual simple interest?

A10 years

B8 years ✓ Correct

C6 years

D12 years

Correct answer: (B) 8 years

Explanation

The sum doubles in 8 years.

Doubling means the simple interest equals the principal, i.e. 100% of it.

Use SI = P x R x T / 100 with interest = P.

So 100 = R x T = 12.5 x T.

T = 100 / 12.5 = 8.

Time for doubling under SI = 100 / R years.

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