Question 549639
the half-life of a particular element is 4 days. 
after 20 days a sample has been reduced to a mass of 0.375g.
what was the initial mass of the sample?
:
the radioactive decay formula: A = Ao*2^(-t/h), where
A = resulting amt after t time
Ao = initial amt
t = time
h = half-life of substance
:
Ao*2^(-20/4) = .375
Ao*2^(-5) = .375
Ao*.03125 = .375
Ao = {{{.375/.03125}}}
Ao = 12 grams, the initial mass of the sample
:
:
Check this on your calc: enter 12*2^(-20/4) result .375