Calculus
posted by Anonymous .
Skeletal remains had lost 81% of the C14 they originally contained. Determine the approximate age of the bones. (Assume the half life of carbon14 is 5730 years. Round your answer to the nearest whole number.)
yr

since the halflife is 5730 years, the amount left after t years is
a = (1/2)^(t/5730)
If 81% is lost, that leaves a = 0.19, then just solve for t.
Since 1/8 < .19 < 1/4, the answer should be between 2 and 3 halflives.