document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=308686>Question 308686</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A medical reseracher wishes to determine the percentage of females who take vitamins. He wishes to be 99% confident that the estimate is within 4% of the true proportion. How large should the sample size be? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #220733 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=220733\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A medical researcher wishes to determine the percentage of females who take vitamins. He wishes to be 99% confident that the estimate is within 4% of the true proportion. How large should the sample size be?<BR>\n" );
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document.write( "z(99.5) = 2.5758<BR>\n" );
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document.write( "Formula:<BR>\n" );
document.write( "n = [z/E]^2(pq)<BR>\n" );
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document.write( "p= 0.5 is the least biased estimate of \"p\", so use it:<BR>\n" );
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document.write( "n = [2.5758/0.04]^2(0.5*0.5) = 1036.7<BR>\n" );
document.write( "Round up to n = 1037\r<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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document.write( " </SPAN>\n" );
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