Madhya Pradesh Police Exam Model Paper 8

Given:
Time = 4 years
Rate = 12.5%
Formula used:
Amount = Simple interest + Principal
$\mathit{S}\mathit{I}=\left(\mathit{P}\mathit{x}\mathit{R}\mathit{x}\mathit{T}\right)/100$
where P = Principal,
R = Rate of Interest,
T = Time Period of the Loan/deposit in years,
SI = Simple Interest
Calculations:
Let, the principal is P
$\mathit{S}\mathit{I}=\left(\mathit{P}\mathit{x}\mathit{R}\mathit{x}\mathit{T}\right)/100$
$\Rightarrow \mathit{P}-400=\left(\mathit{P}\times 4\times 12.5\right)/100$
$\Rightarrow \mathit{P}-400=\mathit{P}\times 4\times \left(1/8\right)$
$\Rightarrow \mathit{P}-400=\mathit{P}/2$
$\Rightarrow 2\mathit{P}-800=\mathit{P}$
$\Rightarrow \mathit{P}=800\mathit{R}\mathit{s}.$
∴ The sum is 800 Rs.