document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1130983>Question 1130983</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A cup of coffee is heated to 180°F and placed in a room that maintains a temperature of 60°F. The temperature of the coffee after t minutes is given by <BR>\n" );
document.write( "T(t) = 60 + 115e&#8722;0.042t.<BR>\n" );
document.write( "(a) Find the temperature, to the nearest degree, of the coffee 20 minutes after it is placed in the room._________°F <BR>\n" );
document.write( "(b) Determine when, to the nearest tenth of a minute, the temperature of the coffee will reach 145°F.______________min </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #747684 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=747684\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A cup of coffee is heated to 180°F and placed in a room that maintains a temperature of 60°F. The temperature of the coffee after t minutes is given by <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=T%28t%29+=+60+%2B+115e%5E%28-0.042t%29 ALIGN=MIDDLE  ALT=\"T%28t%29+=+60+%2B+115e%5E%28-0.042t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( ":<BR>\n" );
document.write( "(a) Find the temperature, to the nearest degree, of the coffee 20 minutes after it is placed in the room._________°F <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=T%28t%29+=+60+%2B+115e%5E%28-0.042%2A20%29 ALIGN=MIDDLE  ALT=\"T%28t%29+=+60+%2B+115e%5E%28-0.042%2A20%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=T%28t%29+=+60+%2B+115e%5E%28-.84%29 ALIGN=MIDDLE  ALT=\"T%28t%29+=+60+%2B+115e%5E%28-.84%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "T(t) = 60 + 115(.4317)<BR>\n" );
document.write( "T(t) = 60 + 49.6<BR>\n" );
document.write( "T(t) = 109.6 degrees after 20 min<BR>\n" );
document.write( ":<BR>\n" );
document.write( "(b) Determine when, to the nearest tenth of a minute, the temperature of the coffee will reach 145°F.______________min<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=60+%2B+115e%5E%28-0.042t%29=+145 ALIGN=MIDDLE  ALT=\"60+%2B+115e%5E%28-0.042t%29=+145\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=115e%5E%28-0.042t%29=+145+-+60 ALIGN=MIDDLE  ALT=\"115e%5E%28-0.042t%29=+145+-+60\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=115e%5E%28-0.042t%29=+85 ALIGN=MIDDLE  ALT=\"115e%5E%28-0.042t%29=+85\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=e%5E%28-0.042t%29=+85%2F115 ALIGN=MIDDLE  ALT=\"e%5E%28-0.042t%29=+85%2F115\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=e%5E%28-0.042t%29=+.739 ALIGN=MIDDLE  ALT=\"e%5E%28-0.042t%29=+.739\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "using nat logs<BR>\n" );
document.write( "-.042t*ln(e) = ln(.739)<BR>\n" );
document.write( "ln(e) = 1, therefore<BR>\n" );
document.write( "-.042t = -302<BR>\n" );
document.write( "t = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-301%29%2F%28-.042%29 ALIGN=MIDDLE  ALT=\"%28-301%29%2F%28-.042%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "t = +7.2 minutes it will be 145 degrees   <BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );