Question

At what rate per cent will a sum of 1200 amount to 1600 in 6 years

Answer 1

Given amount = Rs 1600, sum = Rs 1200, Time = 6 years
Interest = sum*time*rate of interst/100
              = 1200*6*rate of interst/100
              = 72*rate of interest  
Amount = sum + interst
1600 = 1200 + 72*rate of interst
rate of intest = (1600 - 1200)/72 = 400/72 = 5.556%