document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=925537>Question 925537</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Suppose that the standard deviation of the tube life for a particular brand of TV picture tube is known to be &#963; = 500, but the mean operating life is not known. Overall, the operating life of the tubes is assumed to be approximately normally distributed. For a sample of n = 15, the mean operating life is x = 8900 hours. Construct (a) the 95 percent and (b) the 90 percent confidence intervals for estimating the population mean. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #561587 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=561587\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Suppose that the standard deviation of the tube life for a particular brand of TV picture tube is known to be &#963; = 500, but the mean operating life is not known. Overall, the operating life of the tubes is assumed to be approximately normally distributed. For a sample of n = 15, the mean operating life is x = 8900 hours. Construct<BR>\n" );
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document.write( "sample mean = 8900<BR>\n" );
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document.write( "(a) the 95 percent CI<BR>\n" );
document.write( "ME = 1.96*500/sqrt(15) = 253<BR>\n" );
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document.write( "95%CI:: 8900- 253 < u < 8900+253<BR>\n" );
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document.write( "and (b) the 90 percent confidence intervals for estimating the population mean.<BR>\n" );
document.write( "ME = 1.645*500/sqrt(15) = 212<BR>\n" );
document.write( "90% CI:: 8900-212 < u < 8900+212<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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