We’re being asked to **determine how long the age has been dead. **

Recall that ** half-life** is the time needed for the amount of a reactant to decrease by 50% or one-half.

The half-life of a first-order reaction is given by:

$\overline{){{\mathbf{t}}}_{\mathbf{1}\mathbf{/}\mathbf{2}}{\mathbf{}}{\mathbf{=}}{\mathbf{}}\frac{\mathbf{ln}\mathbf{}\mathbf{2}}{\mathbf{k}}}$

where:

**t**_{1/2} = half-life

**k** = decay constant

If a log contains 60.0% of the 14C present in a living tree, how long (yr) has the log been dead? The half-life of 14C is 5715 years. Enter your answer as a whole number with no units.

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