The simple interest on a certain sum of money for 2 1/ 2 yr at 12% per annum is ₹ 20 less than the simple interest on the same sum for 3 1/ 2 yr at 10% per annum. Find the sum.
Correct Answer: ₹ 400
Explanation:
Given, T1 = 5/2, R1= 12% T2= 7/2 yr and R2 = 10%
Let the sum be P.
Then, [(P x 10 x 7)/(100 x 2)] - [(P x 12 x 5)/(100 x 2)] = 20
⇒ (7P/20) - (3P/10) = 20
∴ P = 20 x 20 = ₹ 400
