Question

A sum of money triples itself in 3 years at compound interest. In how many years will it become 9 times itself?

• A. 4
• B. 9
• C. 6
• D. 7

Answer 1

Answer: (C)

(i) Use formula for amount and then use laws of indices.
(ii) Let $3P=P{\left(1+\frac{R}{100}\right)}^3$, find $R$.
(iii) Let $9P=P{\left(1+\frac{R}{100}\right)}^n$, find $n$