document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=387871>Question 387871</A>: <I><SPAN STYLE=\"word-break: break-all;\"> suppose that a student needs to buy 6 books for her clas. the number of books that she will be able to find used is a binomial random variable X with n = 6 and p = .30. In other words the probability that she will find any given book is .30, and is independent from one book to the next.\r<BR>\n" );
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document.write( "What is the probability that she will find exactly 2 books?<BR>\n" );
document.write( "What is the variance for the number of used books she will find V(X)? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #274204 by </B><A HREF=/tutors/aboutme.mpl?userid=user_dude2008><B>user_dude2008(1862)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=user_dude2008><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=274204\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> What is the probability that she will find exactly 2 books?\r<BR>\n" );
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document.write( "(6 choose 2)*(0.3)^2*(1-0.3)^(6-2) = 0.324135\r<BR>\n" );
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document.write( "What is the variance for the number of used books she will find V(X)?\r<BR>\n" );
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document.write( "variance is V(X)=np(1-p) </SPAN>\n" );
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