document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=612276>Question 612276</A>: <I><SPAN STYLE=\"word-break: break-all;\"> construct the probability distribution describing the experiment of rolling a pair of dice 3 times, and counting as x the number of time a total of 9 is rolled. then find the mean and standard deviation of the distribution. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #385397 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=385397\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> construct the probability distribution describing the experiment of rolling a pair of dice 3 times, and counting as x the number of time a total of 9 is rolled. then find the mean and standard deviation of the distribution.<BR>\n" );
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document.write( "Sketch the sample space of 6*6 = 36 sums<BR>\n" );
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document.write( "Count the # of sums not adding up to nine and the number adding up to 9.<BR>\n" );
document.write( "x = 0 ; 32 times ; probability = 32/36 = 8/9<BR>\n" );
document.write( "x = 1 ; 4 times : probability  = 4/36 = 1/9<BR>\n" );
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document.write( "mean = np = (1/9)*36 = 4<BR>\n" );
document.write( "std = sqrt(npq) = sqrt(4*8/9) = 1.8856<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.  </SPAN>\n" );
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