document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1199405>Question 1199405</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A manufacture of TV tube has for many years used a process giving a tube mean life of 4700 hours and standard deviation of 1460 hours. A new process is tried to see if it will increase the life significantly. A sample of 100 new tubes gave a mean life of 4700 hours. Is the new process better than the old at one percent level of significance? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #833289 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=833289\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> i would guess that no improvement, since the mean life of the sample is the same as the mean life that is assumed for the population.<BR>\n" );
document.write( "perhaps an error in the numbers you used?<BR>\n" );
document.write( "z-score would be (4700 - 4700) / (1460 / sqrt(100)) = 0<BR>\n" );
document.write( "area to the left or right of a z-score would be equal to .5.<BR>\n" );
document.write( "that would be well above critical area of .01.<BR>\n" );
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