document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=759322>Question 759322</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Suppose the life of a particular brand of calculator battery is normally distributed with a mean of 75 hours and a standard deviation of 10 hours. If 16 batteries are randomly selected from the population, use Table 4 (Standard Normal probability table), software, or the TI-calculator to find the probability that the sample mean life will be between 70 and 80 hours.  Use the Central Limit Theorem.    </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #462007 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=462007\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Suppose the life of a particular brand of calculator battery is normally distributed with a mean of 75 hours and a standard deviation of 10 hours. <BR>\n" );
document.write( "If 16 batteries are randomly selected from the population, use Table 4 (Standard Normal probability table), software, or the TI-calculator to find the probability that the sample mean life will be between 70 and 80 hours. Use the Central Limit Theorem. <BR>\n" );
document.write( "-----<BR>\n" );
document.write( "t(70) = (70-75)/[10/sqrt(16)] = -5/[10/4] = -20/10 = -2<BR>\n" );
document.write( "---<BR>\n" );
document.write( "t(80) = (80-75)/[10/4] = +2<BR>\n" );
document.write( "----<BR>\n" );
document.write( "P(70< x-bar <80) = P(-2,2,15) = tcdf(-2,2,15) = 0.9361<BR>\n" );
document.write( "================================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "================================<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );