Question

a sum of money lent on simple interest becomes 6 by 5 of itself in 5 years find the rate of simple interest per annum ​

Answer 1

Answer:

4 per cent per year

Step-by-step explanation:

P = initial amount

R = rate of interest per cent per year

T = time period in years

A = final amount at the end of period T

SI = Simple Interest = (P*R*T)/100

A = P + SI

Given:

T = 5

=> SI = (P*R*5)/100 = 5PR/100

A = P + (5PR)/100 ..........(i)

But, we are given that

A = (6/5)*P ...........(ii)

Equating the two identities of A, we get:

=> (6/5)*P = P + (5PR)/100

=> (6/5) = 1 + (5R/100)

=> 6/5 = (100 + 5R)/100

=> 6*100 = 5*(100 + 5R)

=> 600 = 500 + 25R

=> 25R = 100

=> R = 4

The required rate of interest is 4 per cent per year