Posted by Randy on Sunday, June 17, 2012 at 9:34pm.
An artifact was found and tested for its carbon14 content. If 70% 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.

Homework test  Reiny, Sunday, June 17, 2012 at 9:52pm
Use
amount = c (1/2)^(t/k), where k is the halflife period
so ....
.7 = 1(1/2)^(t/5730)
.7 = (2)^(t/5730)
ln .7 = ln ( 2^(t/5730) )
ln .7 = t/5730 (ln2)
t/5730 = ln .7/ln 2 = .514573...
t = 2948.5 years
or 2900 to the nearest 100 years