SOLUTION: The half-life of caffeine is approximately 5.7 hours and a shot of 5-hour Energy contains 200 mg of caffeine. How long after drinking a shot of 5-hour Energy will it take for the a

Question 1005366: The half-life of caffeine is approximately 5.7 hours and a shot of 5-hour Energy contains 200 mg of caffeine. How long after drinking a shot of 5-hour Energy will it take for the amount of caffeine in a person's system to decay to 80mg? Label your answer and round it to one decimal place. Recall: A=A02^-t/h
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
The half-life of caffeine is approximately 5.7 hours and a shot of 5-hour Energy contains 200 mg of caffeine.
How long after drinking a shot of 5-hour Energy will it take for the amount of caffeine in a person's system to decay to 80mg?
Label your answer and round it to one decimal place.
:
Ao*2^(-t/h) = A, where
Ao = 200
A = 80
h = 5.7 hrs
t = time of decay
:
200*2^(-t/5.7) = 80
2^(-t/5.7) =
2^(-t/5.7) = .4
using nat logs
ln(2) = ln(.4)
=
using the calc
= -1.32193
t = -5.7 * -1.32193
t = +7.535 ~ 7.5 hrs to decay to 80 mg

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