clear
//Given
N0=475
N=270.0
t=5.0

//Calculation
//
a=N0/N
l=log(a)/t
T=1/l
T1=0.693/l

//Result
printf("\n (i) The decay constant is %0.3f  /minute",l)
printf("\n (ii) Mean life is %0.2f  minute",T)
printf("\n (iii) Half life is %0.2f  minute",T1)