document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1121957>Question 1121957</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A corporation’s fleet cars have an average annual operating cost of $100,000. Suppose the operating costs are normally distributed with a standard deviation of $8000.<BR>\n" );
document.write( "What is the figure, in thousands of dollars, above which 10% of the operating costs will lie?\r<BR>\n" );
document.write( "\n" );
document.write( "Give the answer to the nearest thousands of dollars and omit the $ sign in your answer (eg, if you think the answer is $100,000, enter 100 into the box).\r<BR>\n" );
document.write( "\n" );
document.write( "Thanks very much </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #737998 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=737998\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> mean is 100,000<BR>\n" );
document.write( "standard deviation is 8,000<BR>\n" );
document.write( "you are looking for the operating costs that are greater than 90% of the operating costs.<BR>\n" );
document.write( "they would be in the top 10%.<BR>\n" );
document.write( "find the z-score where 90% of the area under the normal distribution curve is to the left of it.<BR>\n" );
document.write( "that z-score will be 1.281551567 according to my TI-84 Plus calculator.<BR>\n" );
document.write( "use the z-score formula to find the raw score associated with that.<BR>\n" );
document.write( "the formula is z = (x - m) / s<BR>\n" );
document.write( "z is the z-score<BR>\n" );
document.write( "x is the raw score<BR>\n" );
document.write( "m is the mean<BR>\n" );
document.write( "s is the standard deviation.<BR>\n" );
document.write( "that formula becomes:<BR>\n" );
document.write( "1.281551567 = (x - 100,000) / 8,000.<BR>\n" );
document.write( "solve for x to get x = 1.281551567 * 8,000 + 100,000 = 110,252.4125.<BR>\n" );
document.write( "round that to the nearest thousand and provide it in thousands of dollars and the answer is 110.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "to confirm, i used the following online calculator.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<a  rel=nofollow HREF= \"http://davidmlane.com/hyperstat/z_table.html\" target = \"_blank\">http://davidmlane.com/hyperstat/z_table.html</a>\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "the calculator confirmed that 10% of the operating costs were above 110,252.4.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "here's the what the calculator output looked like.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" src = \"http://theo.x10hosting.com/2018/082805.jpg\" alt=\"$$$\" >\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "bottom line:\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "your answer should be 110.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );