document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=867588>Question 867588</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I need help...\r<BR>\n" );
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document.write( "The shelf life of a battery produced by one major company is known to be normally distributed, with a mean life of 3.9 years and a standard deviation of 0.3 years. What is the probability that a randomly chosen battery will last fewer than 3.2 years?\r<BR>\n" );
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document.write( "Thanks! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #523106 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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=523106\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> First you need the standard z-score\r<BR>\n" );
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document.write( "z = (x - mu)/sigma\r<BR>\n" );
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document.write( "z = (3.2 - 3.9)/0.3\r<BR>\n" );
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document.write( "z = -2.33333333333333\r<BR>\n" );
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document.write( "z = -2.33 <font color=\"blue\">round to 2 decimal places</font>\r<BR>\n" );
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document.write( "Now we use a table like <a  rel=nofollow HREF=\"http://www.deeannef.com/apstats/normal/normtbl2.gif\">this one here</a> to find the area under the standard normal distribution curve that is to the left of z = -2.33\r<BR>\n" );
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document.write( "According to the table, the area is roughly 0.0099 (look in the row that starts with -2.3 and then look in the column that starts with 0.03, where they intersect is at the cell with the number 0.0099 in it)\r<BR>\n" );
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document.write( "So the approximate answer is <font color=\"red\">0.0099</font>\r<BR>\n" );
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document.write( "If you need a more accurate answer, use a calculator that can compute normal cdfs </SPAN>\n" );
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