Question

Amit invests a sum of ₹5400 and Gopal invests a sum of ₹9400 at the same rate of simple interest per annum. If, at the end of 3 years, Gopal gets ₹840 more interest than Amit, then find the rate of interest per annum (in percentage).

• A. 5
• B. 7
• C. 9
• D. 6

Answer 1

Answer:

B. 7

Interest difference comes only from the difference in principal (since rate and time are same).

Difference in principal

$9400 - 5400 = 4000$

Use Simple Interest formula for difference

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

Given:

• Difference in SI = 840

• (P = 4000), (T = 3)

$840 = \frac{4000 \times R \times 3}{100}$

$840 = 120R$

$R = \frac{840}{120} = 7$

Rate of interest = 7% per annum