Question

If a sum of money becomes 4 times of itself in 20 years, what is the rate of interest?

Answer 1

Let the sum of money be x.
Therefore,
Principal =x
Amount=4x
Time=20 years
Interest = amount - Principal
=4x - x
=3x

Interest =P * R * T/100
3x=x *R*20/100
3x/x=R/5
3=R/5
3*5=R
R=15%