Question

Mark (✓) against the correct answer
The simple interest on a sum for $5$ years is $\frac{3}{5}$ of the sum. The rate per cent per annum is
(a) $8\%$
(b) $10\%$
(c) $12\%$
(d) $12\frac{1}{2}\%$

Answer 1

The correct option is (c) $\left(12\%\right)$
Let the sum be $=Rsx$
S.I. for $5$ years is $=Rs.\frac{3}{5}$ of $x$
$=\frac{3x}{5}$
Let the rate be $R\%$ per annum.
then S.I.$=\frac{P\times R\times T}{100}$
$\Rightarrow \frac{3x}{5}=\frac{x\times R\times 5}{100}$
$\frac{3x}{5}=\frac{Rx}{20}$
$R=\frac{3x}{5}\times \frac{20}{x}$
$R=3\times 4$
$\therefore R=12\%$