Question

A sum of money at simple interest becomes four times in 24 years. What is the rate of interest per annum?

• A. $13\frac{3}{4}\%$
• B. $12\frac{1}{2}\%$
• C. $11\frac{3}{4}\%$
• D. $15\frac{4}{9}\%$
• E. None of these

Answer 1

The correct option is B $12\frac{1}{2}\%$

We have, n = 4 and T =24 years.
$\therefore$ Rate of interest $=\frac{100(n-1)}{T}=\frac{100(4-1)}{24}$
$=12\frac{1}{2}\%$