Posted by lance on .
The halflife of 234U, uranium234, is 2.52 105 yr. If 98.4% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

algebra 
Damon,
x = A e^kt
if x/A = 0.5, t = 2.52*10^5
.5 = e^k(2.52*10^5)
ln .5 = .693 = 2.52*10^5 k
k = 2.75*10^6
0.984 = e^2.75*10^6 t
t = 5863 years