A sum doubles in $5$ years at simple interest. In how many years will it become $8$ times at the same rate?

Question

A sum doubles in $5$ years at simple interest. In how many years will it become $8$ times at the same rate?

Option A

25 years

Option B

30 years

Option C — Correct answer

35 years

Correct choice.

Option D

40 years

Explanation

Doubling in $5$ years means the interest in $5$ years equals the principal. To become $8P$, the interest must be $7P$, so the time is $7\times5=35$ years.

Chapter Mock 5: Simple Interest and Compound Interest