document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1202168>Question 1202168</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A bag contains 5 red balls and 4 blue balls. If 2 balls are selected at random, find the probability of selecting 2 red balls  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #836802 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=836802\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "This is a problem that is easily solved using two basic methods.<br><BR>\n" );
document.write( "(1) Select the balls one at a time<br><BR>\n" );
document.write( "P(1st ball is red) = 5/9  (there are 9 balls of which 5 are red)<BR>\n" );
document.write( "P(2nd ball is red) = 4/8  (there are 8 balls left, of which 4 are red)<BR>\n" );
document.write( "P(both balls are red) = (5/9)(4/8) = (5/9)(1/2) = 5/18<br><BR>\n" );
document.write( "(2) Use \"n choose r\"<br><BR>\n" );
document.write( "number of ways of choosing any 2 of the 9 balls: \"9 choose 2\" = (9*8)/(2*1) = 72/2 = 36<BR>\n" );
document.write( "number of says of choosing 2 of the 5 red balls: \"5 choose 2\" = (5*4)/(2*1) = 20/2 = 10<br><BR>\n" );
document.write( "P(choosing 2 of the red balls) = 10/36 = 5/18<br><BR>\n" );
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