Delhi Police Constable Exam Model Paper 10

GIVEN:
Principal = Rs. 10000, Rate = 40% per annum
CONCEPT:
Compound interest earned on $3^{\mathit{r}\mathit{d}}$ year = Amount received after 3 years – Amount received after 2 years.
FORMULA USED:
In case of compound interest:
Amount = $\mathit{P}\times {\left(1+\frac{\mathit{R}}{100}\right)}^{\mathit{T}}$
Where,
P = Principal, R = rate of interest and T = Time
And
CI = Amount – Principal
CALCULATION:
Applying the formula:
Amount received after 2 years = $10000\times {\left(1+\frac{40}{100}\right)}^2=\mathit{R}\mathit{s}.19600$
And
Amount received after 3 years = $10000\times {\left(1+\frac{40}{100}\right)}^3=\mathit{R}\mathit{s}.27440$
∴ Interest for the $3^{\mathit{r}\mathit{d}}$ year = $27440\mathit{–}19600=\mathit{R}\mathit{s}.7840$