document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1047222>Question 1047222</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A certain brand of tyre manufactured by Run Wild Inc. has a lifetime that is normally distributed with a mean of 81,200 miles and a standard deviation of 4,300 miles. For how many miles should they warranty their tyres if they want 95% of them to last longer than the warranty? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #662825 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=662825\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> For 95% to last longer, I need to have z>-1.645<BR>\n" );
document.write( "z=(x-mean)/sd<BR>\n" );
document.write( "-1.645=(x-81200)/4300 units in miles<BR>\n" );
document.write( "Multiply both sides by 4300<BR>\n" );
document.write( "-7073.5=x-81200<BR>\n" );
document.write( "add 81200 to both sides<BR>\n" );
document.write( "x=74126.5 miles<BR>\n" );
document.write( "With a normal distribution with mean 81,200 and sd 4300, 95% of the values will be greater than 74,126.5 miles<BR>\n" );
document.write( " </SPAN>\n" );
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