Compound Interest Ques 9
Question
A man invests a certain sum at compound interest at $10 \%$ per annum for 2 years. He also invests $\frac{1}{3}$ rd less amount at simple interest at $10.5 \%$ per annum. what should be the period of his investment at simple interest so that the compound interest earned is only $75 \%$ of the simple interest earned?
(1) 3 years
(2) 4 years
(3) 5 years
(4) 6 years
(5) None of these
(IBPS Bank PO/MT CWE (Main) 18.11 .2016)
Show Answer
Answer: (2)
Solution: (2)
Let the investment at C.I. be $ \text{₹} x$
$\therefore$ Investment at S.I. $=\frac{2}{3} x$
C.I. $=x\left[\left(1+\frac{10}{100}\right)^{2}-1\right]=\frac{21}{100} x$
S.I. $=\frac{\left(\frac{2}{3} x\right) \times 10.5 \times t}{100}=\frac{7 x t}{100}$
According to the question,
$ \frac{21 x}{100}=\frac{75}{100}\left(\frac{7 x}{100}t\right)$
$ \Rightarrow t=\frac{21 \times 100}{7 \times 75}=4 \text { years }$
BETA
