document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1044665>Question 1044665</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 	<BR>\n" );
document.write( "People were polled on how many books they read the previous year. How many subjects are needed to estimate the number of books read the previous year within one book with 90%  confidence? Initial survey results indicate that sigma<BR>\n" );
document.write( "equals 14.2 books. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #660180 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=660180\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 90% confidence has a z=1.645<BR>\n" );
document.write( "the standard error is sigma/sqrt(n). Their product is the interval.<BR>\n" );
document.write( "z*sigma/sqrt(n)=SE=1.645*14.2/sqrt (n)=23.359/sqrt(n)=1<BR>\n" );
document.write( "Therefore, multiplying both sides by sqrt(n), 23.359=sqrt(n)<BR>\n" );
document.write( "square both sides and n=545.64 or 546\r<BR>\n" );
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