document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1073432>Question 1073432</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 1. 4 DIFFERENT math books and 5 DIFFERENT science books are to be arranged on a shelf. How many possible arrangements can be made if:<BR>\n" );
document.write( "a.the books on the same subject are to be arrange together?<BR>\n" );
document.write( "b.the books are to be arranged alternately\r<BR>\n" );
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document.write( "Pls understand that it says that it is DIFFERENT books.. Please help me because I can't solve it..\r<BR>\n" );
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document.write( "2.There are 4 commuter trains and 5 express busses departing from towns A and B in the morning and 3 commuter trains and 4 express busses operating on the return trip in the evening. In how many ways can a commuter from towns A and Towns B complete a daily round trip via bus or train </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #688266 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=688266\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Note that arrangements are permutations<BR>\n" );
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document.write( "(1.a)  4! * 5! * 2! = 24 * 120 * 2 = 5760 possible arrangements<BR>\n" );
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document.write( "consider the math books and science books as two distinct entities, then you have 2! ways to arrange those two entities<BR>\n" );
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document.write( "(1.b) arrange the science books first, we have<BR>\n" );
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document.write( "5 m 4 m 3 m 2 m 1<BR>\n" );
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document.write( "next arrange the math books<BR>\n" );
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document.write( "5 4 4 3 3 2 2 1 1 = 2880 possible arrangements<BR>\n" );
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