document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1175299>Question 1175299</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Margin of Error for Means<BR>\n" );
document.write( "1.A study of a local high school tried to determine the mean number of text messages that each student sent per day. The study surveyed a random sample of 64 students in the high school and found a mean of 189 messages sent per day with a standard deviation of 80 messages. At the 95% confidence level, find the margin of error for the mean, rounding to the nearest whole number. (Do not write \pm±).\r<BR>\n" );
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document.write( "2.Confidence Intervals for Means<BR>\n" );
document.write( "A study of a local high school tried to determine the mean number of text messages that each student sent per day. The study surveyed a random sample of 55 students in the high school and found a mean of 160 messages sent per day with a standard deviation of 85 messages. Determine a 95% confidence interval for the mean, rounding all values to the nearest whole number. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #801418 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=801418\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> margin of error is t(0.975, df=63)*s/sqrt(n)<BR>\n" );
document.write( "=1.998*80/8=19.98 or 20 messages<BR>\n" );
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document.write( "half-interval is t(0.975,df=54)(*s/sqrt(n))<BR>\n" );
document.write( "=2*85/sqrt(55)<BR>\n" );
document.write( "=22.92 or 23<BR>\n" );
document.write( "(137, 183) units messages<BR>\n" );
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