document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=275992>Question 275992</A>: <I><SPAN STYLE=\"word-break: break-all;\"> As the new city planner for a developing community you need to project a budget for garbage trucks.  To support your numbers you will use an estimate of the mean weight of garbage discarded weekly by household.  \r<BR>\n" );
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document.write( "a.  Find the sample size necessary  to estimate the mean if you want to be 90% confident that the sample mean is within 2 pounds of the true population mean. A sample of 62 households produced a standard deviation = 12.46 pounds\r<BR>\n" );
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document.write( "Try it again at a 95% and a 99% confidence and indicate the change in the sample size and why you think this is so.\r<BR>\n" );
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document.write( "b.  Give an example from your workplace of a problem that requires you to determine a sample size.\r<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 #201236 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=201236\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> As the new city planner for a developing community you need to project a budget for garbage trucks. To support your numbers you will use an estimate of the mean weight of garbage discarded weekly by household. \r<BR>\n" );
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document.write( "a. Find the sample size necessary to estimate the mean if you want to be 90% confident that the sample mean is within 2 pounds of the true population mean. A sample of 62 households produced a standard deviation = 12.46 pounds<BR>\n" );
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document.write( "n = [z*s/E]^2<BR>\n" );
document.write( "n = [invNorm(0.95]*(12.46/(sqrt(62))/2]^2<BR>\n" );
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document.write( "n = [1.96*24.92/sqrt(62)]^2<BR>\n" );
document.write( "n = 38.48<BR>\n" );
document.write( "Round up to n = 39<BR>\n" );
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document.write( "Try it again at a 95%<BR>\n" );
document.write( "Change the z-value to invNorm(0.975)<BR>\n" );
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document.write( "and a 99% confidence<BR>\n" );
document.write( "Change the z-value to invNorm(0.995)<BR>\n" );
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document.write( "and indicate the change in the sample size and why you think this is so.<BR>\n" );
document.write( "More confidence and sample size are directly related.<BR>\n" );
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document.write( "b. Give an example from your workplace of a problem that requires you to determine a sample size.<BR>\n" );
document.write( "I'll leave that to you.<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. \r<BR>\n" );
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