A sum amounts to Rs. 4,260 in 5 years at the rate of 4% p.a. simple interest. What will be the simple interest (in Rs. nearest to a Rs.) on the same sum for 4 15 years at the rate of 8 12 % p.a.? ​ ​

Explanation

Given: A sum amounts to Rs. 4,260 in 5 years at the rate of 4% p.a. simple interest. The same sum for 4 15 years at the rate of 8 12 % p.a. ​ ​ Formula used: S.I = (P × R × T)/100 Amount = P + S.I Where, P = Principal, R = Rate, T = Time and S.I = Simple Interest Calculation: Let the principal be x. S.I = (P × R × T)/100 ⇒ (x × 4 × 5)/100 ⇒ 20 x/100 = x/5 Amount = P + S.I ⇒ 4260 = x + x/5 ⇒ 6 x/5 = 4260 ⇒ x = 3550 Simple interest on the same sum for 4 15 years at the rate of 8 12 % p.a. is, ​ S.I = (3550 × 8 12 × 4 15 )/100 ​ ​ ⇒ (3550 × 17/2 × 21/5)/100 ⇒ 1267.35 ≈ 1267. ∴ The Required Simple Interest is Rs. 1267.