document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=712486>Question 712486</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Each question of a forty-question multiple choice exam has 5 choices, only one of which is correct. Passing requires a minimum score of 70%. A student decides to answer each questions by randomly guessing.<BR>\n" );
document.write( "a) In words, define the random variable<BR>\n" );
document.write( "b) X~_________________________________<BR>\n" );
document.write( "c) How many correct answers is this student expected to get( show some work, including what you entered into calculator)<BR>\n" );
document.write( "d) What is the probability that the student correctly answers the expected number of correct questions <BR>\n" );
document.write( " P(____)=_______________=________________<BR>\n" );
document.write( "e) What is the probability that, by random guessing, the student passes the exam<BR>\n" );
document.write( " P(____)=_______________=________________ </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #438020 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=438020\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Each question of a forty-question multiple choice exam has 5 choices, only one of which is correct. Passing requires a minimum score of 70%. A student decides to answer each questions by randomly guessing.<BR>\n" );
document.write( "a) In words, define the random variable<BR>\n" );
document.write( "b) X = # of questions answered correctly<BR>\n" );
document.write( "c) How many correct answers is this student expected to get( show some work, including what you entered into calculator)<BR>\n" );
document.write( "mean = np = 40*(1/5) = 8<BR>\n" );
document.write( "----------------------------------<BR>\n" );
document.write( "d) What is the probability that the student correctly answers the expected number of correct questions <BR>\n" );
document.write( "P(x = 8)= 40C8(1/5)^8*(4/5)^32 = binompdf(40,1/5,8) = 0.1590<BR>\n" );
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document.write( "e) What is the probability that, by random guessing, the student passes the exam<BR>\n" );
document.write( "Note: 0.7*40 = 28<BR>\n" );
document.write( "P(x >= 28) = 1 - P(40,1/5,27) = 1 - binomcdf(40,1/5,27) = 1.148x10^-11<BR>\n" );
document.write( "=============================================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );