Whats the half-life of Krypton-76 if you originaly have a 1800g sample and after 7104 min u have 225g left?

Question

you have 225g left of the original sample.

Answer 1

[(1/2)^n]*1800 = 225

n = 3
since number of times the sample is halved is 3

7104/3 = 2368 mins.

half life of Kr-76 is 2368 minutes...

Answer 2

Half-life is 2368 minutes because it goes through three half-lives to get to 225g. Thus 7104/3 = 2368.