Posted by Lily on Thursday, December 19, 2013 at 9:59pm.
A persistent organic pollutant is estimated to have a halflife of 30y. If 3 tonnes of the chemical exists in a polluted area today, how much of the chemical will remain after 120y.

Science  DrBob222, Thursday, December 19, 2013 at 11:01pm
k = 0.693/t_{1/2}
Substitute t_{1/2} and solve for k, then substiute into the equation below.
ln(No/N) = kt
No = 3
N = ?
k from above.
t = 120
Substitute and solve for N = tonnes remaining after 120 years