document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1178697>Question 1178697</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A quiz consists of 30 true or false questions. If the student guesses on each<BR>\n" );
document.write( "question, what is the mean and the standard deviation of the number of correct<BR>\n" );
document.write( "answers? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #808298 by </B><A HREF=/tutors/aboutme.mpl?userid=htmentor><B>htmentor(1343)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=htmentor><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=htmentor><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=808298\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> For each question, the probability of answering correctly is 0.5, and the <BR>\n" );
document.write( "questions are independent of each other. This situation is described by<BR>\n" );
document.write( "a binomial probability distribution. The mean of a binomial distribution<BR>\n" );
document.write( "is mu = n*p, where p is the probability of a success and n is the number of <BR>\n" );
document.write( "trials. Thus mu = 0.5*30 = 15.<BR>\n" );
document.write( "The standard deviation is given by sqrt(np(1-p) = sqrt(30/4) = 2.739 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );