document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1058518>Question 1058518</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The travel-to-work time for residents of the 22 largest cities in the United States is reported in the 										<BR>\n" );
document.write( "2003 Information Please Almanac.  Suppose that a preliminary simple random sample of residents										<BR>\n" );
document.write( "of San Francisco is used to develop a planning value of 5.95 minutes for the population standard										<BR>\n" );
document.write( "deviation.										<BR>\n" );
document.write( "										<BR>\n" );
document.write( "a.  If we want to estimate the population mean travel-to-work for San Francisco residents with a										<BR>\n" );
document.write( " margin of error of 2 minutes, what sample size should be used?  Assume 95% confidence.										<BR>\n" );
document.write( "b.  If we want to estimate the population mean travel-to-work for San Francisco residents with a										<BR>\n" );
document.write( " margin of error of 30 seconds, what sample size should be used?  Assume 99% confidence.										<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 #673573 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=673573\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The travel-to-work time for residents of the 22 largest cities in the United States is reported in the 2003 Information Please Almanac. Suppose that a preliminary simple random sample of residents of San Francisco is used to develop a planning value of 5.95 minutes for the population standard	<BR>\n" );
document.write( "deviation.	\r<BR>\n" );
document.write( "\n" );
document.write( "a. If we want to estimate the population mean travel-to-work for San Francisco residents with a margin of error of 2 minutes, what sample size should be used? Assume 95% confidence. <BR>\n" );
document.write( "Since E = z*s/sqrt(n), n = [z*s/E]^2 = [1.96*5.95/2]^2 = 34<BR>\n" );
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document.write( "b. If we want to estimate the population mean travel-to-work for San Francisco residents with a margin of error of 30 seconds, what sample size should be used? Assume 99% confidence.<BR>\n" );
document.write( "n = [2.5758*5.95/(1/2)]^2 = 940 when rounded up<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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