document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1118002>Question 1118002</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A manufacturer claims that the life span of its tires is 51000 miles. You work for a consumer protection agency and you are testing these tires. Assume the life spans of the tires are normally distributed. You select 100 tires at random and test them. The mean life span is 50781 miles. Assume sigma equals 900. <BR>\n" );
document.write( "&#8203;(a) Assuming the&#8203; manufacturer's claim is&#8203; correct, what is the probability that the mean of the sample is 50781 miles or&#8203; less? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #733246 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=733246\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This is a z test for sample means<BR>\n" );
document.write( "z=(x-xbar)/sigma/sqrt)(n)<BR>\n" );
document.write( "z=(50781-51000)/900/10<BR>\n" );
document.write( "z=-219*10/900<BR>\n" );
document.write( "z=-2.43<BR>\n" );
document.write( "prob=0.0075 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );