document.write( "Question 564703:
\n" ); document.write( "The half-life of 234U, uranium-234, is 2.52 105 yr. If 97.4% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed? \r
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Algebra.Com's Answer #365494 by ad_alta(240) $\"\"$ $\"About$

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I'm not sure what you mean by 2.52 105 yr. But I happen to know the half-life is about 246,000 years. So we can find k=ln(1/2)/(-246,000) is about 2.8177E-6. Then we just plug in: 0.974=e^{-kt} and we get t=9,349.56. I suppose that makes 9,000 years if we round down [I personally wouldn't round down: you'll underestimate the time you have to wait before the radiation gets to you!]. \n" ); document.write( "

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