Question

in how much time will a sum of money double itself at 20% per annum simple interest ?

Answer 1

20%............
le the value be 100..
s.i=prt\100
=100*20*1\100
=20
ammount=p+s.i
100+20=120...
increase=20\100*100=20%....

Answer 2

let principal be x
rate=20 %
amount =2x
simple interest =2x-x =x
SI = P*R*T/100
x= x*20*T/100
x= T x/5
5x = Tx
T = 5x/x
T= 5
Time = 5 years