A Ba-133 source had a certified activity of 18 mCi exactly 3 years ago today. Calculate the remaining activity. The half life of Ba-133 is 10.51 years.

Question

Math word problem

Answer 1

The number of half-lives since 3 years ago is n = t/t_½ = 3/10.51.

 

 

To get the activity, use the decay equation A = A₀2^-n.

 

 

A = 18 mCi 2^-(3/10.51) = 14.8 mCi