On my assignment I am really struggling with this question...

Bones A and B are x and y thousand years old respectively. A Geiger Counter confirms that Bone A contains 3 times as much C-14 as Bone B. What can you say about the ages of Bones A and B. Justify your answer

The equation used is

a=15.3 x 0.886^t

Thank you in advanced

You can set up an equation for the ratio of C14 for bone A and bone B:



Now you can manipulate this using logarithms to get an expression for . Post back with what you find and we'll help if you get stuck.

I am not sure why you have the 3 awkwardly placed in that last line, like I know its times 3 but why is it there? Also do I use lo law and bring the ta and tb to the front?
Thank you so much for your help

The 3 isn't awkward - it's the ratio of C14 in Bone A (which I called "") to the amount in Bone B. Thus .

Oh okay, I understand
So then where do I go from there?

Hint: take the log of both sides of the equation.

I think I have it...
I got the answer
Ta/Tb=14.893

Is that correct?

Quote:

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Originally Posted by cbear12345

I think I have it....
I got the answer
Ta/Tb=14.893

Is that correct?

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No, not correct. Please show us the steps you took to get this and we can see where you went wrong.

ln3=ln15.3(0.886)^ta / ln15.3(0.886)^tb
ln3=ta13.5558/tb13.5558
ln3 x 13.5558= ta/tb

hope that makes sense

First step is wrong. It's not true that



Instead note that the 15.3 coefficients cancel out, and use the identity:

ahhh true
so is it

ln3=ta-tb

Getting closer, but you left out the 0.866 factor...