SOLUTION: Dr. Aberli recently found 400 pounds of the rare substance, stutzium, in the tunnels under Atherton. He knows that this rare material has a half life of 60 years. Once there is onl

Question 1090059: Dr. Aberli recently found 400 pounds of the rare substance, stutzium, in the tunnels under Atherton. He knows that this rare material has a half life of 60 years. Once there is only 10 pounds left, it will be safe for students to work with. How long will Dr. Aberli have to wait to use this material in the classroom? (round to the nearest year)
Answer by jorel1380(3719) (Show Source): You can put this solution on YOUR website!
The formula for this radioactive decay would be .5=1 x e^-60k, where .5 equals the half-life, and k equals the radioactive constant. So:
.5=e^-60k
ln 0.5=ln e^-60k
ln 0.5=-60k
k=0.01155245300933242182362053535764
So:
10=400*e^-0.01155245300933242182362053535764*t
.025=e^-0.01155245300933242182362053535764t
ln 0.025=ln e^-0.01155245300933242182362053535764t
t=319.3157 years
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