Akshay invests a sum of Rs. 5400 and Atul invests a sum of Rs. 9400 at the same rate of simple interest per annum. If, at the end of 6 years, Atul gets Rs. 360 more interest than Akshay, then find the rate of interest per annum (in percentage).

Correct option is D

Given:
Akshay's CP = 5400
Atul's CP = 9400
Time = 6 years
Difference in interest after 6 years = 360
Formula Used:
Simple Interest = (P × R × T) / 100
Solution:
​$$\text{Difference in interest} = \frac{(9400 - 5400) \times R \times 6}{100} \\\ \\\frac{4000 \times R \times 6}{100} = 360\\\ \\\frac{24000R}{100} = 360\\\ \\240R = 360\\\ \\R = \frac{360}{240} = 1.5\% \text{ per annum}\\\ \\$$​​
So rate = 1.5% p.a.
Alternate Solution:
Set interest per rupee for 6 years = $$\frac {6R}{100}$$​​
Difference in principal 4000 × $$\frac{6R}{100}$$​= 360
Exam Hall Method: