document.write( "Question 1062936: A scientist has 200 grams of a substance where half of it decays every hour. Write an equation to determine how long it takes until 3.125 grams are remaining \n" ); document.write( "

Algebra.Com's Answer #677940 by Fombitz(32388) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"100=200e%5E%28k%281%2F2%29%29\"$
\n" ); document.write( " $\"e%5E%28k%2F2%29=1%2F2\"$
\n" ); document.write( " $\"k%2F2=1n%281%2F2%29\"$
\n" ); document.write( " $\"k=2%2Aln%281%2F2%29\"$
\n" ); document.write( " $\"k=-2%2Aln%282%29\"$
\n" ); document.write( "So then,
\n" ); document.write( " $\"3.125=200e%5E%28kt%29\"$
\n" ); document.write( " $\"e%5E%28kt%29=3.125%2F200\"$
\n" ); document.write( " $\"kt=ln%281%2F64%29\"$
\n" ); document.write( " $\"kt=-ln%2864%29\"$
\n" ); document.write( " $\"t=-ln%2864%29%2F%28-2ln%282%29%29\"$
\n" ); document.write( " $\"t=-ln%282%5E6%29%2F%28-2ln%282%5E1%29%29\"$
\n" ); document.write( " $\"t=6%2F2%29%29\"$
\n" ); document.write( " $\"t=3\"$ $\"hrs\"$
\n" ); document.write( " \n" ); document.write( "

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