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stuck on maths question

i really dont even know where to begin

the concentration of a drug t hours after the first dose is given by the equation =Ae^-kt (ug/ml)
the initial concentration is 12 ug/ml and after 2 hours the concentration is 6.6 ug/ml

calculate the concentration of the drug after 5 hours
(edited 5 years ago)
Reply 1
Original post by Amberinho
i really dont even know where to begin

the concentration of a drug t hours after the first dose is given by the equation =Ae^-kt (ug/ml)
the initial concentration is 12 ug/ml and after 2 hours the concentration is 6.6 ug/ml

I'm guessing you need to find k and A - please post the whole question in future.

Have you tried plugging in these values? Post all your working.
Is that the full question?

What section of your textbook or whichever book you might be using have you found this in?
Reply 3
Original post by SplittingTheAt0m
Is that the full question?

What section of your textbook or whichever book you might be using have you found this in?


its on a homework test paper thats all i was given in the question
Original post by Amberinho
i really dont even know where to begin

the concentration of a drug t hours after the first dose is given by the equation =Ae^-kt (ug/ml)
the initial concentration is 12 ug/ml and after 2 hours the concentration is 6.6 ug/ml


You find A first by plugging in the initial concentration and t = 0. Then you find k by plugging in the other values and the known value of A.
Reply 5
Original post by alevelphysicist
You find A first by plugging in the initial concentration and t = 0. Then you find k by plugging in the other values and the known value of A.


so ... 12=Ae^-kt which rearranged is 12/e^0=A which is 12?
Original post by Amberinho
so ... 12=Ae^-kt which rearranged is 12/e^0=A which is 12?


yes, so now sub in the second set of values
Reply 7
Original post by alevelphysicist
yes, so now sub in the second set of values


thank you :smile:

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