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 4 years, Atul gets Rs. 720 more interest than Akshay, then find the rate of interest per annum (in percentage).

Correct option is B

Given:

Akshay’s principal = Rs. 5400

Atul’s principal = Rs. 9400

Time = 4 years

Difference in interest = Rs. 720

Rate of interest = ? (Same for both, Simple Interest)

Formula Used:

Simple Interest (SI) is given by:

SI = $$\frac{P \times R \times T}{100}$$​​

Solution:

Let rate be R%

SI(Atul) - SI(Akshay) = 720

​$$\frac{9400 \times R \times 4}{100} - \frac{5400 \times R \times 4}{100} = 720 \\ \ \\\frac{(9400 - 5400) \times R \times 4}{100} = 720\\ \ \\ \frac{4000 \times R \times 4}{100} = 720\\ \ \\\frac{16000R}{100} = 720\\ \ \\160R = 720$$​​

R = $$\frac{720}{160}$$​ = 4.5% per annum