document.write( "Question 1190552: Cesium 137 is a radioactive metal with a short half-life of 30 years. In a
\n" ); document.write( "sample originally having 1 gram of cesium 137, the amount of cesium 137 present after t years is given by A(t) = (1/2)^t/30. where A is the amount of cesium in grams and t is the time in years.\r
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\n" ); document.write( "b. How much cesium 137 will be present after 90 years? \n" ); document.write( "

Algebra.Com's Answer #822243 by ikleyn(52803) $\"\"$ $\"About$

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Cesium 137 is a radioactive metal with a short half-life of 30 years. In a
\n" ); document.write( "sample originally having 1 gram of cesium 137, the amount of cesium 137 present after t years is given by
\n" ); document.write( "A(t) = (1/2)^t/30. where A is the amount of cesium in grams and t is the time in years.
\n" ); document.write( "a. How much cesium 137 will be present after 30 years?
\n" ); document.write( "b. How much cesium 137 will be present after 90 years?
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document.write( "(a)  30 years is one half-life.\r\n" );
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document.write( "     THEREFORE, the remaining mass of the 1 gram of cesium-137 after 30 years is   = 0.5 grams.\r\n" );
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document.write( "     You will get the same answer, if you substitute the value t= 30 years into the given exponential decay function.\r\n" );
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document.write( "(b)  90 years is 3 (three) half-lives.\r\n" );
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document.write( "     THEREFORE, the remaining mass of the 1 gram of cesium-137 after 90 years is   =  =  = 0.125 grams.\r\n" );
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document.write( "     You will get the same answer, if you substitute the value t= 90 years into the given exponential decay function.\r\n" );
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\n" ); document.write( "\n" ); document.write( "On radioactive decay, see the lesson\r
\n" ); document.write( "\n" ); document.write( "    - Radioactive decay problems \r
\n" ); document.write( "\n" ); document.write( "in this site.\r
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\n" ); document.write( "\n" ); document.write( "You will find many similar (and different) solved problems there.\r
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\n" ); document.write( "\n" ); document.write( "        Use this lesson as your handbook, textbook, guide, tutorials, and (free of charge) home teacher.\r
\n" ); document.write( "\n" ); document.write( "        Learn the subject from there once and for all.\r
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\n" ); document.write( "\n" ); document.write( "Also, you have this free of charge online textbook in ALGEBRA-I in this site\r
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.\r
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\n" ); document.write( "\n" ); document.write( "The referred lesson is the part of this online textbook under the topic \"Logarithms\".\r
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\n" ); document.write( "\n" ); document.write( "Save the link to this online textbook together with its description\r
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\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-I
\n" ); document.write( "https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson\r
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\n" ); document.write( "\n" ); document.write( "to your archive and use it when it is needed.\r
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