document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=359712>Question 359712</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me:0<BR>\n" );
document.write( "A car battery is known by the manufacturer to last 65 months with a standard deviation of 4.5 months.<BR>\n" );
document.write( "a. If the manufacturer guarantees them for five years (60 months), what percentage of them will they have to replace?<BR>\n" );
document.write( "b. If the manufacturer does not want to replace more than 4% of the batteries, for how many months should they guarantee them (round to the nearest whole month)?\r<BR>\n" );
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document.write( "thanks you :)<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #256781 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=256781\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A car battery is known by the manufacturer to last 65 months with a standard deviation of 4.5 months.<BR>\n" );
document.write( "a. If the manufacturer guarantees them for five years (60 months), what percentage of them will they have to replace?<BR>\n" );
document.write( "---<BR>\n" );
document.write( "z(60) = (60-65)/4.5 = -1.1111<BR>\n" );
document.write( "--<BR>\n" );
document.write( "%(x < 60) = P(z < -1.1111) = 13.33%<BR>\n" );
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document.write( "b. If the manufacturer does not want to replace more than 4% of the batteries, for how many months should they guarantee them (round to the nearest whole month)?<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Find the z-value with a right tail of 4%.<BR>\n" );
document.write( "invNorm(0.96) = 1.7507<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Find the corresponding raw score value:<BR>\n" );
document.write( "x = zs+u<BR>\n" );
document.write( "x = 1.7507*4.5+65<BR>\n" );
document.write( "x = 72.88 months<BR>\n" );
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document.write( "He should guarantee them for 72 months or 6 years.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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