half life (1 Viewer)

[za]

we had this question in a recent exam. does anybody know how to do this?

"Y-90, radioisotope of yttrium, is used in the treatment of localised cancer. it has a half-life of 64 hours. what percnetage of the initial dose would remain in the patient after 4 days?"


i got 33%, sum1 else got 35%, and another got 37% as the percentage of the initial dose.

just wanna know whose right.

 

[Xayma]

Its 35%, I applied exponential decay and got 35.36%

 

[za]

hhmmmmmmmm...

thnx