document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1040402>Question 1040402</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A recent poll of 700 people who work indoors found that 278 of them smoke. If the researchers want to be 98% confident of their results to within 3.5%, how large a sample is necessary?<BR>\n" );
document.write( "	A.	<BR>\n" );
document.write( "532<BR>\n" );
document.write( "	B.	<BR>\n" );
document.write( "1301<BR>\n" );
document.write( "	C.	<BR>\n" );
document.write( "1062<BR>\n" );
document.write( "	D.	<BR>\n" );
document.write( "751<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #655438 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=655438\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 278/700=0.397<BR>\n" );
document.write( "CI for 1 sample proportion =0.035 here, and that is z (0.99)sqrt { (p)(1-p)/n}; square both sides<BR>\n" );
document.write( "0.035^2=0.001225=z^2(0.99)*p*(1-p)/n<BR>\n" );
document.write( "z(0.99)=2.326<BR>\n" );
document.write( "0.001225=5.410*(.397)(.603)/n; now multiply both sides by n then divide both by 0.001225<BR>\n" );
document.write( "n=5.410*(.397)(.603)/0.001225=1057.  Within rounding error, C would be the choice. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );