A invests ₹ 8,000 and B invests ₹ 11,000 at the same rate of simple interest per annum. If, at the end of 3 years, B gets ₹ 720 more interest than A, then find the rate of simple interest per annum.

Correct option is D

Given:

Investment by A = ₹ 8,000

Investment by B = ₹ 11,000

Time = 3 years

B's interest is ₹ 720 more than A's interest

Formula Used:

Simple Interest is given by the formula:

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

where:

P = Principal

R = Rate of interest per annum

T = Time in years

Solution:

​$$SI_B - SI_A = 720$$​

​$$\frac{11000 \times R \times 3}{100} - \frac{8000 \times R \times 3}{100} = 720$$​

​$$\frac{33000R}{100} - \frac{24000R}{100} = 720$$​

​$$\frac{9000R}{100} = 720$$​

​$$R = \frac{72000}{9000} = 8$$%

The rate of simple interest per annum is 8%.

Thus, option (d) is right.

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