The half-life of 234U, uranium-234, is 2.52 105 yr. If 97.5% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

Question

anonymous · Answer

i came up with 10,000 but its wrong

dumbcow · Answer

what is the half-life?

anonymous · Answer

0.5

kropot72 · Answer

Please clarify the number of years to reach the half life. HThe question states "2.52 105 yr"

dumbcow · Answer

if half-life is 0.5
then amount of time passed at 97.5% is t = 0.01826

dumbcow · Answer

$$e^{-kt} = P_t$$
half-life is t when p = 1/2
solve for k
then plug in p = .975, solve for t