document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1011521>Question 1011521</A>: <I><SPAN STYLE=\"word-break: break-all;\"> As estimate of the mean time of continuous use until an<BR>\n" );
document.write( "answering machine will first require service is desired. If<BR>\n" );
document.write( "it can be assumed that &#945; = 60 days, how large a sample<BR>\n" );
document.write( "is needed so that one will be able to assert with 90%<BR>\n" );
document.write( "confidence that the sample mean is off by at most 10<BR>\n" );
document.write( "days?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #627195 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=627195\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> As estimate of the mean time of continuous use until an<BR>\n" );
document.write( "answering machine will first require service is desired. <BR>\n" );
document.write( "If it can be assumed that &#945; = 60 days, how large a sample<BR>\n" );
document.write( "is needed so that one will be able to assert with 90%<BR>\n" );
document.write( "confidence that the sample mean is off by at most 10<BR>\n" );
document.write( "days?<BR>\n" );
document.write( "---<BR>\n" );
document.write( "E = z*s/sqrt(n)<BR>\n" );
document.write( "----<BR>\n" );
document.write( "Therefore::<BR>\n" );
document.write( "n = [z*s/E]^2<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "Your Problem::<BR>\n" );
document.write( "n = [1.654*60/10] = 9.924^2 = 99 when rounded up<BR>\n" );
document.write( "-----------<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "-----------  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );