document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=971551>Question 971551</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 10. In a poll, 341 out of 775 New York voters surveyed indicated that they approve of the job DeBlasio has done as mayor.  Make a 99% confidence interval for the percentage of all New York voters who would approve of DeBlasio’s performance as mayor.  Describe the meaning of the interval that you found.    <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 #593983 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=593983\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> ph=341/775  = 0.44\r<BR>\n" );
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document.write( "SE= sqrt [p(1-p)/n]= 0.01783\r<BR>\n" );
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document.write( "z.99 ci= 2.576\r<BR>\n" );
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document.write( "z * SE (+/-)= .046\r<BR>\n" );
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document.write( "A 99% CI = [0.394, 0.486]\r<BR>\n" );
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document.write( "We do not know the true proportion of voters who approve.  We are very highly confident that the true value is contained in the interval above.  \r<BR>\n" );
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document.write( "If we were to perform 100 such tests, 99 of them would contain the parameter.  We wouldn't know which 99.  We are 99% confident that a majority of voters do not approve of the job.  We don't say probable, we say confident.  \r<BR>\n" );
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document.write( "It's called confidence, because the true value is either in or out of the interval, and that is a dichotomous issue where probability would be 0 or 1. </SPAN>\n" );
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