document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1087324>Question 1087324</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 1.  Sunshine Stereo sells cd players. The cd players life is normally distributed with a mean of 2.5 years and a standard deviation of 0.4 years. What is the z score for a cd player will break down during the guarantee period of 2 years? \r<BR>\n" );
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document.write( "2.Using Table 3, find the probability\r<BR>\n" );
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document.write( "3.Find the z score so that 25% of the standard normal curve lies to the left of z. \r<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #701604 by </B><A HREF=/tutors/aboutme.mpl?userid=mathmate><B>mathmate(429)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mathmate><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=mathmate><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=701604\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Question:<BR>\n" );
document.write( "1.  Sunshine Stereo sells cd players. The cd players life is normally distributed with a mean of 2.5 years and a standard deviation of 0.4 years. What is the z score for a cd player will break down during the guarantee period of 2 years? <BR>\n" );
document.write( "2.Using Table 3, find the probability<BR>\n" );
document.write( "3.Find the z score so that 25% of the standard normal curve lies to the left of z. <BR>\n" );
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document.write( "Solution:<BR>\n" );
document.write( "&mu;=2.5 years<BR>\n" );
document.write( "&sigma;=0.4 years<BR>\n" );
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document.write( "1. z-score = (x-&mu;)/&sigma;=(2-2.5)/0.4=-1.25<BR>\n" );
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document.write( "2. P(x<2)<BR>\n" );
document.write( "P(x<2)<BR>\n" );
document.write( "=P(z<(2-&mu;)/&sigma;)<BR>\n" );
document.write( "=P(z<(2-2.5)/0.4)<BR>\n" );
document.write( "=P(z<-1.25)<BR>\n" );
document.write( "=0.1056  [ from normal probability tables ]<BR>\n" );
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document.write( "3. P(z<Z)=0.25<BR>\n" );
document.write( "From tables, Z=-0.67449  has an area of 25% on the left tail =><BR>\n" );
document.write( "[This translates to x=(&sigma;Z)+&mu;=2.23 years]<BR>\n" );
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