document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=437886>Question 437886</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A market researcher wants to find a confidence interval estimate of the mean age of all TCC students. A study done earlier in the year found that the standard deviation of all TCC student ages was 14.2 years. How large a random sample must the researcher take in order to be 95% confident that the margin of error is 3.2 years? \r<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #302901 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=302901\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A market researcher wants to find a confidence interval estimate of the mean age of all TCC students. A study done earlier in the year found that the standard deviation of all TCC student ages was 14.2 years. How large a random sample must the researcher take in order to be 95% confident that the margin of error is 3.2 years?<BR>\n" );
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document.write( "Since E = zs/sqrt(n)<BR>\n" );
document.write( "n = [zs/E]^2<BR>\n" );
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document.write( "n = [1.96*14.2/3.2]^2 = 76 when rounded up<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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