document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1178274>Question 1178274</A>: <I><SPAN STYLE=\"word-break: break-all;\"> How large should the size of a random sample be so that we can be 90% certain that the sample mean X will not deviate from the true mean by more than σ/2?\r<BR>\n" );
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document.write( "thank you </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #807567 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=807567\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the error, e,=sigma/sqrt(n)*z(0.95)<BR>\n" );
document.write( "e^2=2.706*sigma^2/n, squaring everything including z=1.645<BR>\n" );
document.write( "e=sigma/2 so e^2=sigma^/4<BR>\n" );
document.write( "so sigma^2/4=2.706 sigma^2/n<BR>\n" );
document.write( "n=10.0824 or 11.\r<BR>\n" );
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