Question

If the simple interest on a certain sum of money is $\frac{4}{25}$th of the sum and the rate per cent equals the number of years, then the rate of interest per annum is

• A. $2$%
• B. $4$%
• C. $5$%
• D. $6$%

Answer 1

Answer: (B)

$4$%

$\Rightarrow$ Let the principal be $Rs.x$.

$\Rightarrow$ Then, Simple Interest = $\frac{4}{25}x.$

$\Rightarrow$ Let the rate of interest per annum be $r\%$ then time ( T)= $r$ years.

$\Rightarrow$ $R=\frac{100\times S.I.}{P\times T}$

$\Rightarrow$ $r=\frac{100\times \frac{4x}{25}}{x\times r}$

$\Rightarrow$ $r^2=\frac{400}{25}$

$\Rightarrow$ $r=\frac{20}{5}=4\%$