clc 
// Given that
t = 2.1 // half life in minute
r = 60 // percentage fraction of sample which decayed 
// Sample Problem 9 on page no. 12.34
printf("\n # PROBLEM 9 # \n")
printf("Standard formula used \n")
printf(" lambda = 0.693 / t_1/2     (Decay constant) \n ")
lambda = 0.693 / t
printf("\n Decay constant is %f per minute.",lambda)