Question

If Rs. 3750 amount to Rs. 4620 in 3 years at simple interest. Find
(i) the rate of interest
(ii) the amount of Rs. 7500 in $5\frac{1}{2}$ years at the same rate of interest

Answer 1

(i) In first case
A= Rs. 4620
P=Rs. 3750
I=A-P=Rs. 4620- Rs. 3750 =Rs. 870
T=3 years
$R=\frac{100\times 1}{P\times T}=\frac{100\times 290}{3750}=\frac{4\times 29}{15}$
$=\frac{116}{15}=7\frac{11}{15}$%
In second case: P= Rs. 7500 $R=\frac{116}{15}$%
$T=5\frac{1}{2}$ years = $\frac{11}{2}$ years
Interest = $\frac{P\times T\times R}{100}$
=$Rs.\frac{7500\times 11\times 116}{2\times 15\times 100}=\frac{250\times 116\times 11}{100}$
=$10\times 29\times 11=290\times 11=Rs.3190$
Amount= $Rs.7500+3190=Rs.10690$