Gopal invests a sum of Rs. 5400 and Akshay invests a sum of Rs. 9400 at the same rate of simple interest per annum. If, at the end of 6 years, Akshay gets Rs. 720 more interest than Gopal, then find the rate of interest per annum (in percentage).

Correct option is C

Given:

Principal invested by Gopal = Rs. 5400
Principal invested by Akshay = Rs. 9400
Time = 6 years
Difference in interest = Rs. 720
Rate of interest is the same for both
Formula Used:
Simple Interest (SI) = (P × R × T) / 100
Solution:
Difference in principal= 9400 − 5400= 4000
According to the question:
​$$\frac{4000 \times R \times 6}{100} = 720 \\\ \\\frac{24000R}{100} = 720\\\ \\240R = 720\\\ \\R = 3\%\\\ \\$$

Rate of interest = 3% per annum