math
posted by mike .
if the rate for radioactive decay for a substance is r=.0063 and time is being measured in days how do you find the halflife of the substance to the nearest hour?

Do you mean
A(t) = Ao e^(.0063 t) ????
If so then
1 = 2 e^(.0063 t)
.5 = e^(.0063 t)
ln .5 = (.0063 t)
.69315 = (.0063 t)
t = 110.02 days which is about 110 days and one hour