document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1076085>Question 1076085</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Express Courier Service has found that the delivery time for packages is normally distributed, with mean 15 hours and standard deviation 2 hours.<BR>\n" );
document.write( "(a) For a package selected at random, what is the probability that it will be delivered in 18 hours or less? (Round your answer to four decimal places.)<BR>\n" );
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document.write( "(b) What should be the guaranteed delivery time on all packages in order to be 95% sure that the package will be delivered before this time? (Hint: Note that 5% of the packages will be delivered at a time beyond the guaranteed time period.) (Round your answer to one decimal place.)<BR>\n" );
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document.write( " hr<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #690759 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=690759\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Express Courier Service has found that the delivery time for packages is normally distributed, with mean 15 hours and standard deviation 2 hours.<BR>\n" );
document.write( "(a) For a package selected at random, what is the probability that it will be delivered in 18 hours or less? (Round your answer to four decimal places.)<BR>\n" );
document.write( "z(18) = (18-15)/2 = 3/2<BR>\n" );
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document.write( "P(x <= 18) = P(z <= 3/2) = normalcdf(-100,3/2) = 0.9332<BR>\n" );
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document.write( "(b) What should be the guaranteed delivery time on all packages in order to be 95% sure that the package will be delivered before this time? (Hint: Note that 5% of the packages will be delivered at a time beyond the guaranteed time period.) (Round your answer to one decimal place.)<BR>\n" );
document.write( "Find the z-value with a left tail of 0.95<BR>\n" );
document.write( "invNorm(0.95) = 1.645<BR>\n" );
document.write( "Find the corresponding time:: t = 1.645*2+15 = 18.29 hrs = 18 hr 17 min 24 sec<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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