Question

At what rate of interest per annum, the simple interest on a certain sum becomes 2/5 times of amount in 10 years at simple interest?

Answer 1

p=100
si=40
r=100(40)\100(10)=4%

Answer 2

Let the principal be:x

Rate be:R

Time given is 10 yrs

Interest becomes 2x/5;

Substituting,

I = (P*R*T)/100;

2x/5= (x*10*R)/100;

Solving:

You get R=4

Ans. Rate= 4 %pa