document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=366430>Question 366430</A>: <I><SPAN STYLE=\"word-break: break-all;\"> PROBLEM 3<BR>\n" );
document.write( "Mall security estimates that the average daily per-store theft is exactly $250, but wants to determine the accuracy of this statistic.  The company researcher takes a sample of 81 clerks and finds<BR>\n" );
document.write( "X(BAR) = $210<BR>\n" );
document.write( "S = $40.\r<BR>\n" );
document.write( "\n" );
document.write( "a) Test at &#945; = .001<BR>\n" );
document.write( "b) Construct a 90% CIE of &#956;\r<BR>\n" );
document.write( "\n" );
document.write( "I Tried this for Part a\r<BR>\n" );
document.write( "\n" );
document.write( "Z = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+%28210-250%29%2F%2840%2F+sqrt%28+210%2F81+%29+%29+ ALIGN=MIDDLE  ALT=\"+%28210-250%29%2F%2840%2F+sqrt%28+210%2F81+%29+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > and I got 9. From there I get confused and don't know what to do next or even if my first answer for part a is right.\r<BR>\n" );
document.write( "\n" );
document.write( "Any help would be greatly appreciated. If you can explain how you got the answer that would be even better.<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 #261167 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=261167\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Mall security estimates that the average daily per-store theft is exactly $250, but wants to determine the accuracy of this statistic.  The company researcher takes a sample of 81 clerks and finds<BR>\n" );
document.write( "X(BAR) = $210<BR>\n" );
document.write( "S = $40.\r<BR>\n" );
document.write( "\n" );
document.write( "a) Test at alpha = .001<BR>\n" );
document.write( "b) Construct a 90% CIE of u\r<BR>\n" );
document.write( "\n" );
document.write( "Feedback:<BR>\n" );
document.write( "Part a::::<BR>\n" );
document.write( "Ho: u = 250<BR>\n" );
document.write( "Ha: u is not equal to 250<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "I use a t-statistic for mean problems involving sample size.<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "The critical values are +/-3.416337<BR>\n" );
document.write( "The test statistic is t(210) =  (210-250)/(40/ sqrt(81)) = -9<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "Conclusion: Since the ts is in the rejection interval,<BR>\n" );
document.write( "reject Ho.<BR>\n" );
document.write( "===========================<BR>\n" );
document.write( "Part b:::<BR>\n" );
document.write( " Construct a 90% CIE of u<BR>\n" );
document.write( "---<BR>\n" );
document.write( "x=bar = 210<BR>\n" );
document.write( "E = 1.6641 = 7.3961<BR>\n" );
document.write( "---<BR>\n" );
document.write( "90% CIE: 210-7.3961 < u < 210+7.3961<BR>\n" );
document.write( "90% CIE: 202.6039 < u < 217.3961<BR>\n" );
document.write( "=======================================<BR>\n" );
document.write( "Let me know if this helps.<BR>\n" );
document.write( "=======================================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "----<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );