SOLUTION: How old is a skeleton that has lost 75% of its Carbon-14? I have NO idea how to do this problem. Could someone help me?

Question 33363: How old is a skeleton that has lost 75% of its Carbon-14? I have NO idea how to do this problem. Could someone help me?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
The half-life of Carbon-14 is 5700 years
The formula you need is
Amount you now have= (Amount you started with)(1/2)^(t/5700)
You want the "Amount you now have" to be 75% of "Amount you started with".
EQUATIOn:
Let the original amount be "x".
0.75x=x(1/2)^(t/5700) where t is the number of years
0.75=(1/2)^(t/5700)
Take the natural log of both sides to get:
ln(0.75)=(t/500)[ln(1/2)]
t/5700= [ln0.75]/[ln(1/2)]
t/5700=0.415037...
t=2365.71 years.
Cheers,
Stan H.
RELATED QUESTIONS
how old is a skeleton that has 95% of its carbon-14... (answered by solver91311)

The radioactive element carbon-14 has a half-life of 5750 years. The percentage of... (answered by ankor@dixie-net.com)

A skeleton contains one hundredth of its original amount of its original amount of... (answered by stanbon)

A radioactive substance has a decay rate of 1.8% per year. What is its half life? Give... (answered by ankor@dixie-net.com)

This one would be the decay model? Can someone walk me through this, please? In carbon (answered by ankor@dixie-net.com)

Having trouble getting started and really appreciate any assistance/direction. An... (answered by stanbon)

I could really use some help here. This is a crazy difficult problem. I am almost done... (answered by josgarithmetic)

If anyone can help me solve this, I would be so appreciative. This is day two of trying... (answered by josgarithmetic,greenestamps)

In order to determine the age of a piece of wood, the amount of carbon-14 was measured.... (answered by greenestamps,ikleyn)