Correct Answer - Option 3 : Rs. 1000
Given:
Sum borrowed by Atanu = Rs. 4000
Rate % = 12% per annum
Sum lent by Atanu = (4000 + x)
Rate at which sum lent by atanu = 16% per annum
Profit earned in entire transaction = Rs. 320
Formula Used:
Simple Interest = (Principal × Rate × Time)/100
Calculation:
Simple interest need to be paid by Atanu = (4000 × 12 × 1)/100
⇒ Simple interest need to be paid by Atanu = Rs. 480
Simple Interest earned by Atanu after lending Rs. (4000 + x) = Rs. 480 + Rs. 320 = Rs. 800
800 = [(4000 + x) × 16 × 1]/100
⇒ (4000 + x) = (800 × 100)/16
⇒ (4000 + x) = 5000
⇒ x = 5000 - 4000 = Rs. 1000
∴ The Sum added by Atanu while lending is Rs. 1000.