document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1183831>Question 1183831</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Question 5<BR>\n" );
document.write( "A sociologist found that in a random sample of 50 retired men, the average number of jobs they had during their lifetimes was 7.2. The population standard deviation is 2.1.\r<BR>\n" );
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document.write( "a. Find the best point estimate of the population mean.\r<BR>\n" );
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document.write( "b. At 80% confidence level, estimate the margin of error. \r<BR>\n" );
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document.write( "c. Find the 80% confidence interval of the mean number of jobs.\r<BR>\n" );
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document.write( "d. How large a sample would be required if you want to be 99% confidence within 0.05?\r<BR>\n" );
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document.write( "e. Estimate the sample mean if at 95% confidence level, the confidence intervals is 52.3 < 𝜇 < 55.7.\r<BR>\n" );
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document.write( "f. Find the error bound at 80% confidence level using the 80% confidence interval calculated. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #814307 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=814307\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Point estimate is 7.2 the sample value<BR>\n" );
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document.write( "80% CI half interval is z(0.90)*sigma/sqrt(n)<BR>\n" );
document.write( "=1.282*2.1/sqrt(50)<BR>\n" );
document.write( "=0.38. This is the margin of error (B)<BR>\n" );
document.write( "the interval is (6.82, 7.58) units jobs (C)<BR>\n" );
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document.write( "error=z(0.995)*sigma/sqrt(n)<BR>\n" );
document.write( "0.05=2.576*2.1/sqrt(n)<BR>\n" );
document.write( "sqrt(n)=2.576*2.1/0.05=108.192<BR>\n" );
document.write( "square both sides and n=11705.50 or 11706 people<BR>\n" );
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document.write( "The mean will be in the middle or 54.0<BR>\n" );
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document.write( "The error bound for the 80% interval is 7.58-7.2 or 0.38 jobs\r<BR>\n" );
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document.write( " </SPAN>\n" );
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