document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1131856>Question 1131856</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A researcher wishes to estimate the mean amount of money spent per month on food by households in a certain neighborhood. She desires a margin of error of  . Past studies suggest that a population standard deviation of   is reasonable. Estimate the minimum sample size needed to estimate the population mean with the stated accuracy </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #748589 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=748589\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> To do this, one needs to know the sd, margin of error required, and the confidence.<BR>\n" );
document.write( "if 95% confidence, the half-interval or margin of error, is 1.96*sd/sqrt(n), where n is the sample size and the sd is presumed known.  If the sd is not known, one needs a t-value, a little more complicated but basically the same approach. </SPAN>\n" );
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