document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=233879>Question 233879</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The average lifespan for batteries is 90 hours with a standard deviation of 12 hours. Construct a confidence interval at the 95% confidence level. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #172626 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=172626\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The average lifespan for batteries is 90 hours with a standard deviation of 12 hours. Construct a confidence interval at the 95% confidence level.<BR>\n" );
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document.write( "sample mean: 90<BR>\n" );
document.write( "standard error: 1.96*12 = 23.52<BR>\n" );
document.write( "95% CI: 90-23.52 < u < 90+23.52<BR>\n" );
document.write( "95% CI: 66.48 < u < 113.52<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );