Question

A 40 gram sample of a substance thats used for drug research has a k-value of 0.1455. Find the substance's half-life,in days. Round your answer to the nearest tenth.

Answer 1

do you know how to solve
\[\large e^{-.1455t}=.5\] for \(t\) ?
write in equivalent logarithmic form as
\[-.455t=\ln(.5)\] then solve for \(t\) with a calculator

Answer 2

you get
\[t=-\frac{\ln(.5)}{.1445}\]

Answer 3

@satellite73 : Slight typo in your previous post - should read "-1.455t', not "-.455t" ...