Question

In how many years will a sum of money doubles itself at 5% per annum on simple interest?

Answer 1

20 years

let the initial sum be 10

given 5% interest per annum (0.5 in case of 10)

by these calculations we can summarise it by

let the initial sum be x

then,Amount=2x(because sum will be double)

Amount = Principal + S.I

2x = x + s.I

S.I = x

S.I = (p*r*t)/100

x = (x*5*t)/100

therefore,t = 20 years