Vijay invests a sum of Rs. 5400 and Mohan invests a sum of Rs. 9400 at the same rate of simple interest per annum. If, at the end of 6 years, Mohan gets Rs. 600 more interest than Vijay, then find the rate of interest per annum (in percentage).

Correct option is D

Given:
Vijay’s Principal = Rs. 5400
Mohan’s Principal = Rs. 9400
Time = 6 years
Difference in interest = Rs. 600
Formula Used:
​$$\text{Simple Interest=} \dfrac{P \times R \times T}{100} \\\ \\ \text{Difference in SI= } \dfrac{(P_M - P_V) \times R \times T}{100}$$​​
Solution:
​$$\begin{aligned}&\dfrac{(9400 - 5400) \times R \times 6}{100} = 600 \\&\dfrac{4000 \times 6 \times R}{100} = 600 \\&240R = 600 \\&R = \dfrac{600}{240} = 2.5\end{aligned}$$​​
The rate of interest = 2.5% per annum