algebra
posted by suzie .
An artifact was found and tested for its carbon14 content. If 84% of the original carbon14 was still present, what is its probable age (to the nearest 100 years)? Use that carbon14 has a halflife of 5,730 years.

0.84 = (0.50)^(t/5730)
t/5730 = log0.85/log0.50 = 0.23447
t = 1343 years
(Round it to 1300 years) 
The halflife of 234U, uranium234, is 2.2.52 x 10 5th power years. If 97.4% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?