document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=609841>Question 609841</A>: <I><SPAN STYLE=\"word-break: break-all;\"> an isotope of strontium 90 has a half life of 38 years. if you have 500 mg of this isotope today, how many milligrams (to the nearest tenth) will you have in 19 years? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #383965 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=383965\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> an isotope of strontium 90 has a half life of 38 years. if you have 500 mg of this isotope today, how many milligrams (to the nearest tenth) will you have in 19 years?<BR>\n" );
document.write( "exponential growth/decay equation<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=A+=+Aoe%5E%28kt%29 ALIGN=MIDDLE  ALT=\"A+=+Aoe%5E%28kt%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "where<BR>\n" );
document.write( "A is amount after time t<BR>\n" );
document.write( "Ao is the initial amount<BR>\n" );
document.write( "k is the growth/decay constant<BR>\n" );
document.write( "t is time<BR>\n" );
document.write( ".<BR>\n" );
document.write( "From: \"an isotope of strontium 90 has a half life of 38 years.\" we can determine k:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=.5Ao+=+Aoe%5E%28k%2A38%29 ALIGN=MIDDLE  ALT=\".5Ao+=+Aoe%5E%28k%2A38%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "dividing both sides by Ao:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=.5+=+e%5E%28k%2A38%29 ALIGN=MIDDLE  ALT=\".5+=+e%5E%28k%2A38%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%28.5%29+=+38k ALIGN=MIDDLE  ALT=\"ln%28.5%29+=+38k\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%28.5%29%2F38+=+k ALIGN=MIDDLE  ALT=\"ln%28.5%29%2F38+=+k\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-.01824+=+k ALIGN=MIDDLE  ALT=\"-.01824+=+k\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "Now, we can answer:<BR>\n" );
document.write( "if you have 500 mg of this isotope today, how many milligrams (to the nearest tenth) will you have in 19 years?<BR>\n" );
document.write( "starting with:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=A+=+Aoe%5E%28-.01824t%29 ALIGN=MIDDLE  ALT=\"A+=+Aoe%5E%28-.01824t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=A+=+500e%5E%28-.01824%2A19%29 ALIGN=MIDDLE  ALT=\"A+=+500e%5E%28-.01824%2A19%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=A+=+500%28.7071%29 ALIGN=MIDDLE  ALT=\"A+=+500%28.7071%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=A+=+354.55 ALIGN=MIDDLE  ALT=\"A+=+354.55\"   DISABLED_style= \"max-width:90%; height:auto;\" > mg\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );