A wooden artifact from an ancient tomb contains 30 percent of the carbon-14 that is present in living trees. How long ago was the artifact made? (The half-life of carbon-14 is 5730 years.)
Your answer is ? years.

Question

A wooden artifact from an ancient tomb contains 30 percent of the carbon-14 that is present in living trees. How long ago was the artifact made? (The half-life of carbon-14 is 5730 years.) 
Your answer is    ?  years.

anonymous · Answer

formula is$$Q=Q_0(\frac{1}{2})^{\frac{t}{5700}}$$

anonymous · Answer

so you need to solve 
$$.30=(\frac{1}{2})^{\frac{t}{5700}}$$ for t

anonymous · Answer

take the log
$$ln(.3)=\frac{t}{5700}ln(\frac{1}{2})$$ solve for t to get 
$$t=5700\frac{ln(.3)}{ln(.5)}$$

anonymous · Answer

now use a calculator

anonymous · Answer

i get 9900