Question

URGENT PLEASE HELP!!!!

The liver filters the drug Tylenol in an exponential way. Suppose tests show that after 12 hours pass, since taking a does of 400 milligrams, 50 milligrams remain in the blood stream. What is the half life of of Tylenol?

Possible answers:
6.5 hours
4 hours
No correct answer

Answer 1

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Answer:

  4 hours

Step-by-step explanation:

There are several ways to work this. One way that often works well with multiple choice questions is "try the answers".

6.5 hours

  If the half-life is 6.5 hours, then 200 mg will remain after 6.5 hours, and 100 mg will remain after 13 hours. The decay rate is faster than that, so 6.5 hours is not right, but a lesser value is.

4 hours

  If the half-life is 4 hours, then 200 mg will remain after 4 hours, and 100 mg will remain after 4 more (=8) hours. An additional 4 hours will cut that in half again to 50 mg after 12 hours.

The half-life is 4 hours.