Question

1. Find the amount and the compound interest on Rs.$10000$ in $3$ years,if the interest for the successive years are $10$%,$15$% and $20$%.
2.At what rate percent per annum will Rs.$4000$ amount to Rs.$4410$ in $2$ years when interest is compounded annually?

Answer 1

$1$.

$A=P(1+\frac{R_1}{100})(1+\frac{R_2}{100})(1+\frac{R_3}{100})$

$=10000(1+\frac{10}{100})(1+\frac{15}{100})(1+\frac{20}{100})$

$=10000\times \frac{11}{10}\times \frac{23}{20}\times \frac{6}{5}$

$A=15180$

$C.I=A-P$

$=15180-10000=Rs.5180$

$2$.

$A=P{(1+\frac{R}{100})}^t$

$4410=4000{(1+\frac{R}{100})}^2$

$\sqrt{\frac{4410}{4000}}=1+\frac{R}{100}$

$R=\frac{100}{20}=5$

$5$% per annum