document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=670665>Question 670665</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A survey of 36 \"iPhone\" owners showed that the purchase price has a sample mean of $450 with a sample standard deviation of $175.\r<BR>\n" );
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document.write( "a) Compute the 95% confidence interval for the mean.<BR>\n" );
document.write( "b) How large a sample is needed to estimate the population mean within $10 at a 99% confidence level?\r<BR>\n" );
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document.write( "Please show all work, calculations, and formulas!! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #417093 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=417093\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A survey of 36 \"iPhone\" owners showed that the purchase price has a sample mean of $450 with a sample standard deviation of $175. <BR>\n" );
document.write( "a) Compute the 95% confidence interval for the mean.<BR>\n" );
document.write( "x-bar = 450<BR>\n" );
document.write( "ME = 1.96*175/sqrt(6) = 9.5278<BR>\n" );
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document.write( "95%CI: 450-9.5278 < u < 450+9.5278<BR>\n" );
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document.write( "b) How large a sample is needed to estimate the population mean within $10 at a 99% confidence level? <BR>\n" );
document.write( "n = [z*s/E]^2<BR>\n" );
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document.write( "n = [2.5758*175/10]^2 = 2032 when rounded up<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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