Question

at simple interest a sum becomes 6/5 of itself in 5/2 years. the rate of interest per annum is

Answer 1

Simple interest factor :

Principle × rate × time

Let the principle be p :

The interest is :

P × r × 2.5 = 2.5pr

1.2p

1.2p = p + 2.5pr

0.2p = 2.5pr

r = 0.2/2.5

r = 0.08

r = 0.08 × 100 = 8%