document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=868633>Question 868633</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A doctor's office would like to estimate the proportion of couples that will not allow their child to receive the new vaccine with a 90% confidence interval. From a tiny sample, 26% of parents will not allow the new vaccine. Using this information, how many couples must be sampled in order for the estimate to be within 3% of the true proportion? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #523713 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=523713\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A doctor's office would like to estimate the proportion of couples that will not allow their child to receive the new vaccine with a 90% confidence interval. From a tiny sample, 26% of parents will not allow the new vaccine. Using this information, how many couples must be sampled in order for the estimate to be within 3% of the true proportion?<BR>\n" );
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document.write( "Since E = z*sqrt(pq/n),<BR>\n" );
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document.write( "n = [z/E]^2*pq<BR>\n" );
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document.write( "n = [1.645/0.03]^2*(0.26*0.74) = 575 when rounded up<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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