Question

Radium-226 has a half-life of 1620 years. for a 150 gram sample, how many grams will remain after 200 years?

Answer 1

ah, yes

if you start with P amount of something and the half life is h units (in years) and the time elapsed is t (in years) then the amount left is A

the equation is

`A=P((1)/(2))^(t)/(h)`


so
given
h=1620
P=150
t=200
so

`A=150((1)/(2))^(200)/(1620)`

`A=150((1)/(2))^(10)/(81)`
use your calculator
A≈137.69781917515g
about 138grams left