document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=242320>Question 242320</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The mass m(t) remaining after t hours from a 50 gram sample of a radioactive substance is given by the equation m(t)= 50e^-0.0578t. after how long will 30 grams of substance remain? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #177388 by </B><A HREF=/tutors/aboutme.mpl?userid=nerdybill><B>nerdybill(7384)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=nerdybill><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/cgi-bin/show-face.mpl?user=nerdybill><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=177388\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">     The mass m(t) remaining after t hours from a 50 gram sample of a radioactive substance is given by the equation m(t)= 50e^-0.0578t. after how long will 30 grams of substance remain?<BR>\n" );
document.write( ".<BR>\n" );
document.write( "m(t)= 50e^-0.0578t<BR>\n" );
document.write( "the problem gives m(t) as 30 you simply need to solve for t:<BR>\n" );
document.write( "30= 50e^-0.0578t<BR>\n" );
document.write( "30/50 = e^-0.0578t<BR>\n" );
document.write( "ln(30/50) = -0.0578t<BR>\n" );
document.write( "(ln(30/50))/-0.0578 = t<BR>\n" );
document.write( "8.838 hours = t<BR>\n" );
document.write( " </SPAN>\n" );
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