document.write( "Question 194634: you need to express the problem as an exponential function whose value is the percentage of the remaining thorium after x million years, and then use the function and the following two properties to find the age of meteorite in million years:\r
\n" ); document.write( "\n" ); document.write( "The level of thorium in a sample decreases by a factor of one-half every 2 million years. A meteorite is discovered to have only 8.6% of its original thorium remaining. How old is the meteorite? Thank you \n" ); document.write( "
Algebra.Com's Answer #146021 by stanbon(75887)\"\" \"About 
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The level of thorium in a sample decreases by a factor of one-half every 2 million years. A meteorite is discovered to have only 8.6% of its original thorium remaining. How old is the meteorite?
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\n" ); document.write( "A(t) = Ao*(1/2)^(t/2*10^6)
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\n" ); document.write( "0.086Ao = Ao*(1/2)^(t/(2 million))
\n" ); document.write( "(1/2)^(t/2 million) = 0.086
\n" ); document.write( "Take the log to get:
\n" ); document.write( "(t/2 million) = log(0.086)/log(1/2) = 3.53951953
\n" ); document.write( "t = (2 million)*(3.53951953)\r
\n" ); document.write( "\n" ); document.write( "t = 7,079,039.06
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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