Posted by martha on Wednesday, April 4, 2012 at 4:59pm.
only 5% of the carbon14 in a small wooden bowl remains , how old is the bowl?
Hint, halflife for carbon –14 us 5730 years

math  Reiny, Wednesday, April 4, 2012 at 5:26pm
Since this is a "halflife" situation we can use
1/2 or .5 as the base in our exponential equation
5 = 100 (1/2)^(t/5730)
.05 = .5 ^(t/5730)
take ln of both sides
ln 0.05 = (t/5730) ln 0.5
t/5730 = ln 0.05/ln 0.5 = 4.3219...
t = appr 24765 years 
math  Bruce, Wednesday, February 27, 2013 at 10:06pm
Unless your teacher gives you 5700 as the half life.