document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1086022>Question 1086022</A>: <I><SPAN STYLE=\"word-break: break-all;\"> You read about a survey in a newspaper and find that 70% of the 250 people sampled prefer Candidate A. You are surprised by this survey because you thought that more like 50% of the population preferred this candidate. Based on this sample, is 50% a possible population proportion? Compute the 95% confidence interval to be sure. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #700166 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=700166\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 95%CI is mean +/-1.96*SE<BR>\n" );
document.write( "mean is point estimate, here 0.70<BR>\n" );
document.write( "SE is sqrt (p*(1-p))/n, or sqrt (.21/250)=0.0290<BR>\n" );
document.write( "interval width is 0.0568, after multiplying by 1.96<BR>\n" );
document.write( "CI is {0.643, 0.757)<BR>\n" );
document.write( "No, 50% is not a possible proportion.  It is not in the interval.<BR>\n" );
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