document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1121356>Question 1121356</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A clothing store manager takes a random sample of 40 sales for the day. From this sample the manager calculated that the mean sale amount per customer was $88 with a standard deviation of $12. Assume that sales per customer is approximately normally distributed. Construct a 99% confidence interval for the mean sales per customer.<BR>\n" );
document.write( "$82. 90 to $93.10<BR>\n" );
document.write( "$79.50 to $95. 60<BR>\n" );
document.write( "$82.00 to $94.00<BR>\n" );
document.write( "$76.00 to $100.00<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #737235 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=737235\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This is a t-interval and 99% with df=39 is 2.708<BR>\n" );
document.write( "the half interval is +/- t*s/sqrt (n)=2.708*12/sqrt(40)<BR>\n" );
document.write( "That is 5.14\r<BR>\n" );
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document.write( "interval is (82.86, 93.14) , the first choice </SPAN>\n" );
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