document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=654024>Question 654024</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The lifetime of a certain manufacturer's washing machine is normally distributed with mean 4 years. Only 15 percent of all these washing machines last at least 5 years. What is the standard deviation of the lifetime of a washing machine made by this manufacturer?\r<BR>\n" );
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document.write( "Thanks so much!!! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #408624 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=408624\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The lifetime of a certain manufacturer's washing machine is normally distributed with mean 4 years. Only 15 percent of all these washing machines last at least 5 years. What is the standard deviation of the lifetime of a washing machine made by this manufacturer? <BR>\n" );
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document.write( "Find the z-value with a right tail of 15%: invnorm(0.85) = 1.0364<BR>\n" );
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document.write( "Solve for standard deviation using x = z*s + u<BR>\n" );
document.write( "5 = 1.0364*s + 4<BR>\n" );
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document.write( "1.0364*s = 1<BR>\n" );
document.write( "s = 0.9648<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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