document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1193182>Question 1193182</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A sociologist found that in a sample of 50 retired men, the average number of jobs they had during their lifetimes was 7.2. The population standard deviation is 2.1.<BR>\n" );
document.write( "a) Find the best point estimate of the mean.<BR>\n" );
document.write( "b) Find the 95% confidence interval of the mean number of jobs. <BR>\n" );
document.write( "c) Find the 99% confidence interval of the mean number of jobs. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #825187 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=825187\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Best point estimate is from the sample, 7.2 jobs<BR>\n" );
document.write( "95% half-interval is z(0.975)*sigma/sqrt(n)<BR>\n" );
document.write( "=1.96*2.1/sqrt(50)<BR>\n" );
document.write( "=0.58 hours<BR>\n" );
document.write( "interval is (6.62, 7.78) hours <BR>\n" );
document.write( "-<BR>\n" );
document.write( "half-interval is 2.576*2.1/sqrt(50)<BR>\n" );
document.write( "=0.765 hours<BR>\n" );
document.write( "(6.43, 7.97) hours </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );