Question

At what rate percent of simple interest will the interest on Rs. 3750 be one-fifth of itself in 4 years? To what will it amount in 15 years?

Answer 1

P= Rs. 3750
I= Rs. $3750\times \frac{1}{5}$
=Rs. 750
T=4 years
R= $\frac{100\times I}{P\times T}$
=$\frac{100\times 750}{3750\times 4}$
= $\frac{100\times 750}{3750\times 4}$
=5%
Again, P=Rs. 3750
Interest of 4 years= Rs. 750
Interest of 1 year=Rs. $\frac{750}{4}$
Interest of 15 years = Rs. $\frac{750}{4}\times 15$
=Rs. $\frac{750\times 15}{4}$
=Rs. $\frac{5625}{2}$
=Rs.2812.50
Amount in 15 years will be =Rs. 3750 +Rs. 2812.50
=Rs. 6562.50
$\therefore$ Rate =5%
Amount in 15 years will be =Rs. 6562.50