The half life of a certain tranquilizer in the bloodstream is 42 hours. How long will it take for the drug to decay to 88% of the original dosage?

Question

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Answer 1

1/2 = e^rt = e^42r

ln(1/2) = 42r

r = ln(1/2)/42 = -1.65% decay rate per hour

.88= e^-.0165t

lin.88 = -.0165t

t = ln.88/-..0165 = 7.75 hours