document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1162812>Question 1162812</A>: <I><SPAN STYLE=\"word-break: break-all;\"> There are 3 math books and 3 history books that are to be arranged on a shelf. How many different ways can the books be arranged on the shelf if:\r<BR>\n" );
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document.write( "A) Two history books are to be kept together, and 2 mathematics books are also kept together?<BR>\n" );
document.write( "B) Two math books should immediately follow the 2 history books, and vice versa?\r<BR>\n" );
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document.write( "(A & B are separate from each other)\r<BR>\n" );
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document.write( "Thank you so much!  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #786727 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=786727\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "A)...<br><BR>\n" );
document.write( "3C2 = 3 ways to choose the two history books that are to be together as a unit<BR>\n" );
document.write( "2P1 = 2 ways to order those two history books<BR>\n" );
document.write( "3C2 = 3 ways to choose the two math books that are to be together as a unit<BR>\n" );
document.write( "2P1 = 2 ways to order those two math books<BR>\n" );
document.write( "4P4 = 24 ways to order the four units (pair of history books, pair of math books, single history book, and single math book)<br><BR>\n" );
document.write( "ANSWER: 3*2*3*2*24 = 864<br><BR>\n" );
document.write( "B)...<br><BR>\n" );
document.write( "Grammatically, this makes no sense with the given numbers of books.<br><BR>\n" );
document.write( "\"... and vice versa\" means there are two math books following two history books, and two history books following two math books.  That would mean there have to be four history books... but there are only three.<br><BR>\n" );
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