document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=999924>Question 999924</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A student is preparing for an upcoming midterm exam. The professor given the student 40 practice questions and plans to select 12 of the questions at random to create the midterm exam. Suppose the student knows how to correctly answer 34 of the 40 questions. Let X represent the number of questions the student answers correctly on the exam.<BR>\n" );
document.write( "(a) What is the probability distribution of X?<BR>\n" );
document.write( "(b) What is the probability that the student will know how to answer at least 10 questions on the exam? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #617453 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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=617453\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A student is preparing for an upcoming midterm exam. The professor given the student 40 practice questions and plans to select 12 of the questions at random to create the midterm exam. Suppose the student knows how to correctly answer 34 of the 40 questions. Let X represent the number of questions the student answers correctly on the exam.<BR>\n" );
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document.write( "Binomial Problem with n = 12 and p(getting answer correct) = 34/40 = 17/20<BR>\n" );
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document.write( "(a) What is the probability distribution of X?<BR>\n" );
document.write( "mean = np = 12*(17/20) = 10.2<BR>\n" );
document.write( "std = sqrt[npq] = sqrt[10.2*3/20] = 1.24<BR>\n" );
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document.write( "(b) What is the probability that the student will know how to answer at least 10 questions on the exam?<BR>\n" );
document.write( "P(10<= x <=12) = 1-P(0<= x <=9) = 1- binomcdf(12,17/20,9) = 0.7358<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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document.write( " </SPAN>\n" );
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