document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1109719>Question 1109719</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The average speed of winds in a certain city equals 11 mph. Assume that wind speeds are approximately normally distributed with a standard deviation of 3.5 mph.\r<BR>\n" );
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document.write( "(a) Find the probability that the wind speed on any one reading will exceed 13.5 mph.<BR>\n" );
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document.write( "(b) Find the probability that the mean of a random sample of twelve readings will exceed 13.5 mph. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #724705 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=724705\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The average speed of winds in a certain city equals 11 mph. Assume that wind speeds are approximately normally distributed with a standard deviation of 3.5 mph. <BR>\n" );
document.write( "(a) Find the probability that the wind speed on any one reading will exceed 13.5 mph.<BR>\n" );
document.write( "z(13.5) = (13.5-11)/3.5 = 2.5/3.5 = 0.7143<BR>\n" );
document.write( "P(x > 13.5) = P(z > 0.7143) = normalcdf(0.7143,100) = 0.2375<BR>\n" );
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document.write( "(b) Find the probability that the mean of a random sample of twelve readings will exceed 13.5 mph.<BR>\n" );
document.write( "z(13.5) = (13.5-11)/[3.5/sqrt(12)] = 2.4744<BR>\n" );
document.write( "P(x-bar > 13.5) = P(z > 2.4744) = normalcdf(2.4744,100) = 0.0067<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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