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- Quantitative Aptitude
Suneeta borrowed certain sum from Reena for $2 \,yr$ at simple interest. Suneeta lent this sum to Venu at the same rate for $2 \,yr$ at compound interest. At the end of $2 \,yr$, she received $Rs. 110$ as compound interest but paid $Rs. 100$ as simple interest. Find the sum and the rate of interest?
$Rs. 250$ , rate $10 \%$ pa
$Rs. 250$ , rate $20 \%$ pa
$Rs. 250$ , rate $25 \%$ pa
$Rs. 250$ , rate $30 \%$ pa
Solution
Let the sum borrowed be Rs. P Rate of interest $= R \%$ $CI = Rs. 110, SI = Rs .100,$ Time $( t )=2$ years
$CI – SI =110-100=10$
$\Rightarrow$ Difference $=\frac{P R^{2}}{(100)^{2}} \Rightarrow 10=\frac{P R^{2}}{(100)^{2}}$
$\Rightarrow$ Difference $=\frac{S I \times R}{200} \Rightarrow 10=\frac{100 \times R}{200} ; R=20 \%$
Put value (ii) in (i)
$\Rightarrow 10=\frac{P(20)^{2}}{(100)^{2}} ; P=R s .250$
