document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1153190>Question 1153190</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A manufacturer claims that the mean lifetime, <BR>\n" );
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document.write( ", of its light bulbs is <BR>\n" );
document.write( "45\r<BR>\n" );
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document.write( "months. The standard deviation of these lifetimes is <BR>\n" );
document.write( "4\r<BR>\n" );
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document.write( "months. Ninety bulbs are selected at random, and their mean lifetime is found to be <BR>\n" );
document.write( "44\r<BR>\n" );
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document.write( "months. Can we conclude, at the <BR>\n" );
document.write( "0.05\r<BR>\n" );
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document.write( "level of significance, that the mean lifetime of light bulbs made by this manufacturer differs from <BR>\n" );
document.write( "45\r<BR>\n" );
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document.write( "months? <BR>\n" );
document.write( "Perform a two-tailed test. Then fill in the table below. <BR>\n" );
document.write( "Carry your intermediate computations to at least three decimal places, and round your responses as specified in the table. <BR>\n" );
document.write( "The null hypothesis:<BR>\n" );
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document.write( "The alternative hypothesis:<BR>\n" );
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document.write( "1<BR>\n" );
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document.write( "The type of test statistic:\r<BR>\n" );
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document.write( "The value of the test statistic:<BR>\n" );
document.write( "(Round to at least three decimal places.)\r<BR>\n" );
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document.write( "The two critical values at the <BR>\n" );
document.write( "0.05\r<BR>\n" );
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document.write( "level of significance:<BR>\n" );
document.write( "(Round to at least three decimal places.)<BR>\n" );
document.write( "and\r<BR>\n" );
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document.write( "Can we conclude that the mean lifetime of light bulbs made by this manufacturer differs from 45 months? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #775377 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52908)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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/cgi-bin/show-face.mpl?user=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=775377\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .\r<BR>\n" );
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document.write( "Please use an &nbsp;APPROPRIATE &nbsp;format for your posts to this forum.\r<BR>\n" );
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document.write( "Otherwise, &nbsp;you will &nbsp;<U>regularly</U> &nbsp;find your posts in the &nbsp;TRASH &nbsp;SECTION, &nbsp;<U>zeroed</U>.\r<BR>\n" );
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