document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1102406>Question 1102406</A>: <I><SPAN STYLE=\"word-break: break-all;\">  A quiz consists of 20 multiple-choice questions, each with 4 possible answers. For someone who makes random guesses for all of the answers, find the probability of passing if the minimum passing grade is 60 %. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #717119 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=717119\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Each question has a 0.25 probability of being right<BR>\n" );
document.write( "Want 12 or more right<BR>\n" );
document.write( "start with 12, 20C12(0.25^12)(0.75^8)=0.0008\r<BR>\n" );
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document.write( "20C13*0.25^13*0.75^7=0.0002-- both are 0.0009 if the rounding is done only at the end.<BR>\n" );
document.write( "20C14*0.25^14*0.75^6=0.000026<BR>\n" );
document.write( "Probability is 0.0009<BR>\n" );
document.write( "Expected value is 5, np, and variance is 5(.75)=3.75, so sd is sqrt (3.75)=1.94, so this is about 3.5 sd s from mean of 5. </SPAN>\n" );
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