document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1197914>Question 1197914</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A researcher wants to estimate the mean blood cholesterol level of young men ages 15-25 with a 81.26% confidence interval. The blood cholesterol level of young men follows a Normal distribution with standard deviation  = 30 mg/dl. How large a sample would the researcher need to take to estimate the mean blood cholesterol to within 9 mg/dl?<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 #831408 by </B><A HREF=/tutors/aboutme.mpl?userid=ewatrrr><B>ewatrrr(24785)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ewatrrr><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=ewatrrr><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=831408\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ME+=+z%2Asigma%2Fsqrt%28n%29 ALIGN=MIDDLE  ALT=\"ME+=+z%2Asigma%2Fsqrt%28n%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "0r<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=n+=+%28z%2Asigma%2FME%29%5E2 ALIGN=MIDDLE  ALT=\"n+=+%28z%2Asigma%2FME%29%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "81.26% confidence interval  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28100-81.26%29%2F2 ALIGN=MIDDLE  ALT=\"%28100-81.26%29%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" >= 9.7%  z(.8126 + .097) = 1.34 <BR>\n" );
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document.write( " <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=n+=%2830%2A1.34%2F9%29%5E2 ALIGN=MIDDLE  ALT=\"n+=%2830%2A1.34%2F9%29%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 19.98  (always round Up )<BR>\n" );
document.write( "n = 20 </SPAN>\n" );
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