1. ## Half life problem...

The half-life of carbon-14 is 5600 years. If a piece of charcoal made from the wood of a tree shows only 67%
of the carbon-14 expected in living matter, when did the tree die?

2. ## Re: Half life problem...

$Pe^{kt} = \dfrac{P}{2}$ when $t = 5600$. Solve for $k$.

$Pe^{kt} = .67P$ when you plug in the value for k you got above. Solve for t.

3. ## Re: Half life problem...

Is k the 67%?

4. ## Re: Half life problem...

No. The .67 is 67%.

5. ## Re: Half life problem...

What is K then?

6. ## Re: Half life problem...

P = starting weight of the carbon-14
k = constant of exponential decay for carbon-14 - can be found by solving the first formula I gave.
t = time in years