document.write( "Question 324617: Suppose that 5 grams of a radioactive substance decreases to 4 grams in 30 seconds. What is its half-life to the nearest tenth of a second? \n" ); document.write( "

Algebra.Com's Answer #232378 by Fombitz(32388) $\"\"$ $\"About$

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$\"N=N0e%5E%28kt%29\"$
\n" ); document.write( " $\"+4=5e%5E%28k%2830%29%29\"$
\n" ); document.write( " $\"e%5E%2830k%29=4%2F5\"$
\n" ); document.write( " $\"30k=ln%284%2F5%29\"$
\n" ); document.write( " $\"k=ln%284%2F5%29%2F30\"$
\n" ); document.write( " $\"k=-0.007438\"$
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( " $\"e%5E%28kt%29=1%2F2\"$
\n" ); document.write( " $\"kt=ln%281%2F2%29\"$
\n" ); document.write( " $\"t=ln%281%2F2%29%2F%28-0.007438%29\"$
\n" ); document.write( " $\"t=93.2\"$
\n" ); document.write( "The half life is 93.2 seconds. \n" ); document.write( "

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