SSC Sample Paper Mock Test-15 SSC CGL Tear-II Paper-1

A man invests half his capital at the rate of 10% per annum, one-third at 9% and the rest at 12% per annum. The average rate of interest per annum, which he gets, is

A) 9%

B) 10%

C) 10.5%

D) 12%

Correct Answer: B

Solution :

Let the principal be Rs. x.

\[\therefore \] \[{{I}_{1}}=\frac{x\times 10\times 1}{2\times 100}\]= Rs. \[\frac{x}{20}\]

\[{{I}_{2}}=\frac{x\times 9\times 1}{3\times 100}\]= Rs. \[\frac{3x}{20}\]

\[{{I}_{3}}=\frac{x}{6}\times \frac{12\times 1}{100}\]= Rs. \[\frac{x}{50}\]

\[\therefore \] \[{{I}_{1}}+{{I}_{2}}+{{I}_{3}}\]= Rs. \[\left( \frac{x}{20}+\frac{3x}{100}+\frac{x}{50} \right)\]

= Rs. \[\left( \frac{5x+3x+2x}{100} \right)\]= Rs. \[\frac{x}{10}\]

\[\therefore \] Average annual rate =10%