SOLUTION: A particular pain relieving medicine has a decay rate of 16 % per hour. A patient was given a dose of the medicine 7 hours ago and there is currently 66 milligrams of the medicine

Question 1040382: A particular pain relieving medicine has a decay rate of 16 % per hour. A patient was given a dose of the medicine 7 hours ago and there is currently 66 milligrams of the medicine in the patients bloodstream.
What was the original dose of the medicine? _________ milligrams
How long will the patient need to wait for there to be less than 25 % of the original dose of the medicine left in their bloodstream?
Express your answer as a decimal to the nearest tenth of an hour. _______hours
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = the original dose of medicine

mg original dose
-------------------------------

Take the log of both side

In 8 hrs less than 25% of the original dose will
be in the bloodstream
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