Question

a and b borrowed rupees 3000 rupees 3500 respectively at the same rate of simple interest for 3 years if we paid rupees 150 more interest that you find the rate of interest per annum

Answer 1

S. I. of A
principal = 3000
rate = R%
time = 3years
S. I. = (3000*R*3)/100
= 90R

S. I. of B
principal = 3500
rate = R
time = 3years
S. I. = (3500*R*3)/100
= 105R

105R - 90R = 150
15R = 150
R = 150/15
R = 10

Therefore, rate = 10%

Answer 2

A borrowed 3000

interest=r

B borrowed 3500

n=3

Interest paid by B=  

100

pnr

​  

=  

100

(3500)(3)(r)

​  

 

=105r

Interest paid by A=  

100

pnr

​  

=  

100

(3000)(3)(r)

​  

 

=90r

Given, 105r−90r=150

r(15)=150

⇒r=10

∴ rate of interest =10% per annum.