document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1183214>Question 1183214</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The mean annual cost of automobile insurance is R95. Assume that the population standard deviation is R14. What is the probability that a simple random sample of size 30 for automobile insurance policies will have a sample mean less than R90 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #813474 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=813474\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> this is a z-test with z=(x bar-mean)/sigma/sqrt (n)<BR>\n" );
document.write( "z < (90-95)/14/sqrt(30)<BR>\n" );
document.write( "z < -5*sqrt(30)/14 inverting and multiplying to deal with division.<BR>\n" );
document.write( "z < -1.956<BR>\n" );
document.write( "0.0252 is probability<BR>\n" );
document.write( "The sd of the sampling distribution is 14/sqrt(30) or 2.556<BR>\n" );
document.write( "Then it is z < -5/2.556 </SPAN>\n" );
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