Chemistry
posted by Leyah .
The halflife of radon222 is 3.82 days. If a sample of gas contains 4.38ug of radon222, how much will remain in the sample after 15.2 days?

k = 0.693/t_{1/2}
Substitute k into the following:
ln(No/N) = kt
No = 4.38 ug.
N = solve for this.
k from above.
t = 15.2 days.