document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1035065>Question 1035065</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A study of peach trees found that the average number of peaches per tree was 525.  The standard deviation of the population is 140 peaches per tree.  A scientist wishes to find the 80% confidence interval for the mean number of peaches per tree.  How many trees does she need to sample to obtain an average accurate to within 14 peaches per tree? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #649690 by </B><A HREF=/tutors/aboutme.mpl?userid=addingup><B>addingup(3677)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=addingup><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=addingup><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=649690\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Margin of Error (half of confidence interval) 14<BR>\n" );
document.write( "The margin of error is defined as the \"radius\" (or half the width) of a confidence interval for a particular statistic.<BR>\n" );
document.write( "Level of Confidence 80<BR>\n" );
document.write( "s = Sample standard deviation 140<BR>\n" );
document.write( "'z critical value' from Look-up Table for 80% 1.28<BR>\n" );
document.write( "significant digits 2<BR>\n" );
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document.write( "n = (1.28*140/14)^2<BR>\n" );
document.write( "n = Sample Size 163.84 = 164 <BR>\n" );
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