Compound Interest Questions and Answers

Interest for the second year

$= text{ Rs. } Big(48 + frac{8 times 48 times 1}{100} Big) = text{ Rs. } 51.84$

$because$ Compounded half yearly

$therefore$ 1 year = 2 half year

and rate 10% annually = $frac{10}{2}$ half yearly

= 5%

$because text{ C.I. } = text{P }Big[big(1+frac{r}{100}big)^n -1 Big] = 10,000$

$= Big[big(1+frac{5}{100}big)^2 -1 Big] = 10,000 times frac{41}{400} = 1,025$

$text{ Required amount } = frac{9261 times 20 times 20 times 20 }{21 times 21 times 21} = 8,000$

$text{P} = frac{1}{Big(1 + frac{tr}{100}Big)} = frac{1000}{Big(1 + frac{10r}{100}Big)}$
$= frac{10000}{10 + r} quad ... (text{I})$

$=\genfrac{}{}{0ex}{}{10000}{10+r}...(\text{I})$

Again

$text{P } = frac{1250}{Big(1 + frac{15r}{100}Big)} = frac{1250 times 20}{20 + 3r} quad ... (text{II})$

By equation I and II

$frac{10000}{10 + r} = frac{1250 times 20}{ 20 + 3r}$

$therefore quad frac{20 + 3r}{10 + r} = frac{1250 times 20 }{10000}$

$quad therefore quad r = 10$

$therefore quad$ Now on putting the value of $r$ in eq. I we get

$text{P } = frac{10000}{10 + 10 } = 500$