document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=927115>Question 927115</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A company manufacturing light bulbs claims that an average light bulb lasts 300<BR>\n" );
document.write( "days. A potential customer randomly selects 15 bulbs for testing. The sampled bulbs<BR>\n" );
document.write( "last an average of 290 days, with a standard deviation of 50 days. If the company’s<BR>\n" );
document.write( "claim were true, what is the probability that 15 randomly selected bulbs would have<BR>\n" );
document.write( "an average life of no more than 290 days? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #562764 by </B><A HREF=/tutors/aboutme.mpl?userid=ewatrrr><B>ewatrrr(24785)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ewatrrr><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=ewatrrr><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=562764\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> mean = 300<BR>\n" );
document.write( "P(x &#8804; 290) = P( z < -10/(50/sqrt(15)) =P(z < -.7746) <BR>\n" );
document.write( "Using a TI calculator 0r similarly a Casio fx-115 ES plus<BR>\n" );
document.write( "P(x &#8804; 290) =P(z < -.7746) = normalcdf(-100, -.7746)= .2193  0r 21.93% </SPAN>\n" );
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