document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=179440>Question 179440</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hello dear tutor, <BR>\n" );
document.write( "I need help with a certain math problem today that we just learned in class, but I can only get how to do really with like an actual example from my homework, which is why I am here, trying to learn! So here is the question! Thanks so much for helping out! it means ALOT! \r<BR>\n" );
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document.write( "Radon-222 is a gas that escapes from rocks and soil. It can accumulate in buildings and can be dangerous for people who breathe it. Radon-222 decays to polonium and eventually to lead. \r<BR>\n" );
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document.write( "a. Find the percent decrease in the amount of radon-222 each day.\r<BR>\n" );
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document.write( "b. Write an exponential decay function for th amount of a 500 mg sample of radon-222 remaining after t days.\r<BR>\n" );
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document.write( "c. How much of the radon-222 sample would remain after 14 days?<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #134393 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=134393\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> You left this out of your post but it is essential information for your problem: \"The most stable isotope, 222Rn, has a half-life of 3.8 days\"<BR>\n" );
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document.write( "Radon-222 is a gas that escapes from rocks and soil. It can accumulate in buildings and can be dangerous for people who breathe it. Radon-222 decays to polonium and eventually to lead. \r<BR>\n" );
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document.write( "a. Find the percent decrease in the amount of radon-222 each day.<BR>\n" );
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document.write( "Percent means per hundred<BR>\n" );
document.write( "So set up a proportion and solve for \"x\":<BR>\n" );
document.write( "x/100 = (1/2)/3.8<BR>\n" );
document.write( "Cross-multiply to get:<BR>\n" );
document.write( "3.8x = 50 <BR>\n" );
document.write( "x = 12.88<BR>\n" );
document.write( "Ans: 12.88%<BR>\n" );
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document.write( "b. Write an exponential decay function for the amount of a 500 mg sample of radon-222 remaining after t days. <BR>\n" );
document.write( "General Formula: A(t) = A(0)*(1/2)^(t/3.8)<BR>\n" );
document.write( "Your problem:<BR>\n" );
document.write( "A(t) = 500(1/2)^(t/3.8)<BR>\n" );
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document.write( "c. How much of the radon-222 sample would remain after 14 days?<BR>\n" );
document.write( "A(14) = 500(1/2)^(14/3.8)<BR>\n" );
document.write( "A(14) = 500(1/2)^3.6842..<BR>\n" );
document.write( "A(14) = 500*0.0777933...<BR>\n" );
document.write( "A(14) = 38.8967.. mg<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.\r<BR>\n" );
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