document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1040398>Question 1040398</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% confidence interval of the true proportion of cars costing over $700,000? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #655200 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=655200\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% confidence interval of the true proportion of cars costing over $700,000? <BR>\n" );
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document.write( "p-hat = 80/400 = 1/5 = 0.2<BR>\n" );
document.write( "ME = z*sqrt[p*q/n]<BR>\n" );
document.write( "z = invNorm(0.995) = 2.5758<BR>\n" );
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document.write( "ME = 2.5758*sqrt[(1/5)(4/5)/400] = 0.0515<BR>\n" );
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document.write( "CI form:: p-hat - ME < p < p-hat + ME<BR>\n" );
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document.write( "99% CI:: 0.2-0.0515 < p < 0.2+0.0515<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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