document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=136541>Question 136541</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The lifetime of a certain brand of battery is known to have a standard deviation of 23  hours. Suppose that a random sample of 70  such batteries has a mean lifetime of 35.1  hours. Based on this sample, find a 95% confidence interval for the true mean lifetime of all batteries of this brand. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #100012 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=100012\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The lifetime of a certain brand of battery is known to have a standard deviation of 23 hours. Suppose that a random sample of 70 such batteries has a mean lifetime of 35.1 hours. Based on this sample, find a 95% confidence interval for the true mean lifetime of all batteries of this brand.<BR>\n" );
document.write( "x-bar = 35.1<BR>\n" );
document.write( "E = 1.96 = 5.38801...<BR>\n" );
document.write( "-----------<BR>\n" );
document.write( "95% CI:(35.1-5.38801 < u < 35.1+5.38801)<BR>\n" );
document.write( "====================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );