document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=386229>Question 386229</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A 20-minute Oil and Lube service claims that their average service time is no more than 20 minutes. A random sample of 40 service times was collected, and the sample mean was found to be 21.3 minutes, with a sample standard deviation of 5.5 minutes. Is there evidence to reject the claim at the alpha = 0.05 level? Perform an appropriate hypothesis test, showing the necessary calculations and/or explaining the process used to obtain the results. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #273049 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=273049\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A 20-minute Oil and Lube service claims that their average service time is no more than 20 minutes. <BR>\n" );
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document.write( "A random sample of 40 service times was collected, and the sample mean was found to be 21.3 minutes, with a sample standard deviation of 5.5 minutes. <BR>\n" );
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document.write( "Is there evidence to reject the claim at the alpha = 0.05 level? <BR>\n" );
document.write( "Perform an appropriate hypothesis test, showing the necessary calculations and/or explaining the process used to obtain the results.<BR>\n" );
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document.write( "Ho: u <= 20 min (claim)<BR>\n" );
document.write( "Ha: u > 20 min<BR>\n" );
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document.write( "test statistic:<BR>\n" );
document.write( "t(21.3) = (21.3-20)/[5.5/sqrt(40)] = 1.4949<BR>\n" );
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document.write( "p-value = P(t > 1.4949 when df=39) = 0.0715<BR>\n" );
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document.write( "Since the p-value is greater than 5%, fail to reject Ho.<BR>\n" );
document.write( "Conclusion: The test results support the claim.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. <BR>\n" );
document.write( " </SPAN>\n" );
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