document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1196928>Question 1196928</A>: <I><SPAN STYLE=\"word-break: break-all;\">  One pump can fill a gas tank in 8 hours. With a second pump working simultaneously, the tank can be filled in 3 hours. How long would it take the second pump to fill the tank operating alone?<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 #829980 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=829980\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "The response from the other tutor shows a typical formal algebraic solution.<br><BR>\n" );
document.write( "Here are a couple of less formal methods for solving this kind of problem, if formal algebra is not required.<br><BR>\n" );
document.write( "(Note, however, that even if a formal algebraic solution is required, you can get good mental exercise (and good problem-solving experience) by solving the problem using logical reasoning.)<br><BR>\n" );
document.write( "One common alternative to the solution method shown by the other tutor is to consider the least common multiple of the two given times, which is 24 hours.<br><BR>\n" );
document.write( "In 24 hours the one pump could fill the tank 24/8 = 3 times; in 24 hours the two pumps together could fill the tank 24/3 = 8 times.<br><BR>\n" );
document.write( "That means the other pump could fill the tank 8-3 = 5 times in 24 hours; and that means it could fill the one tank in 24/5 hours, or 4 4/5 hours, or 4 hours 48 minutes.<br><BR>\n" );
document.write( "And another solution method using logical reasoning is that, because the one pump can fill the tank alone in 8 hours and the two pumps together can fill it in 3 hours, in those 3 hours the one pump can fill 3/8 of the tank.<br><BR>\n" );
document.write( "That means in those 3 hours the other pump can fill 5/8 of the tank; and that means the number of hours required for the other pump alone to fill the tank is 3(8/5) = 24/5 hours.<br><BR>\n" );
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