half-life t1/2 for 214Bi is 19.7 min. sample is 4.0 microCi what will the activity be after 1.313 hr?

Answer 1

It is hard to understand the question when you put it up like that. But here is a way to do it: Take the original amount of the element and multiply it by .5 and to the power of the number of half-lives it has done. So (element) X (.5)^(Number of half-lives)