Posted by devin on Monday, December 5, 2011 at 7:38pm.
99 what? 99 grams? 99 tons? 99%. I suspect 99%.
Two steps. First determine k.
k = 0.693/t1/2 and substitute into the following:
ln(No/N) = kt
I would set No = 100 if that is 99%.
Then N = 1% (if 99% is gone)
k from above
Solve for t in years.
Sorry don't understand it is 99 percent
Ln(100)/1)=(0.693/t^1/2)(t). ??? Don't get it
There isn't anything to get. Can you punch the calculator? That's all there is to it. Do it in steps. Don't try to muddle it up by putting all of it together.
ln 100/1 = 4.605
0.693/28.1 = 0.02466 = k
so
ln(100/1) = 0.02466*t
4.605 = 0.02466t
and t = 4.605/0.02466 = ? or about 200 years more or less.
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