Concept of “Simple Interest”-09

Question: In certain years, a sum of money is doubled itself at 6.25 % simple interest per annum, then the required time will be [SSC (CGL), 2015 Tier-1]  [Ans. (d) 16 years]

(a) 12.5 years   (b) 8 years (c) 10  years (d) 16 years

Detailed Explanation: Concept: 1. “In simple interest, “Principal” remains constant throughout the period."

2. “Rate of simple interest is the interest on rupees 100 for one year”

First Method: Let Principal = 100, then the Amount = 200 and SI = 200-100=100

The Rate of interest is 6.25% pan, i. e., Rs 6.25 is SI on Rs. 100, so Rs.100 will be obtained in (100/6.25 )= 16 years

Second Method: Let Principal = P, Amount = A. Then, given that