Question

the simple interest on rupees 800 will be invested a certain rate of interest per annum for 4 air is equal that on rupees 625 when invested for 8 years at a rate of 4 per annum find the rate of interest per annum in the first case?

Answer 1

Let the rate of intrest in first case =x%

In first case,
Principal amount=₹800
Time=4years
Rate=x%
Si=p×r×t/100
=800×x×4/100
=32x
SI in first case=32x

In second case,
Principal amount=₹625
Time=8years
Rate=4%
SI=p×r×t/100
si=625×4×8/100
So SI in second case=₹200
A/q
First case si and second case si is equal .

32x=200
x=200/32
$x = \frac{25}{4}$
$x = 6 \times \frac{1}{4}\%$
Rate=
$6 \times \frac{1}{4} \%$