document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1085640>Question 1085640</A>: <I><SPAN STYLE=\"word-break: break-all;\"> the distribution of cholesterol levels in teenage boys is approximately normal with a mean of 170 and a standard deviation of 30.  what is the minimum cholesterol level of the top quintile (top fifth) of teenage boys to the nearest whole number?\r<BR>\n" );
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document.write( "I do not understand how to work this?\r<BR>\n" );
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document.write( "Thank you<BR>\n" );
document.write( "Julia<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 #699809 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=699809\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the top fifth is 80% to 100% since 5 * 20% = 100%<BR>\n" );
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document.write( "check the z-tables for the z-score associated with 80% ( minimum of the top fifth)<BR>\n" );
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document.write( "0.84 = (X - 170) / 30<BR>\n" );
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document.write( "X - 170 = 30 * 0.84<BR>\n" );
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document.write( "X = 170 + (30 * 0.84) = 195.2<BR>\n" );
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document.write( "the minimum cholesterol level of the top quintile (top fifth)<BR>\n" );
document.write( "of teenage boys is<BR>\n" );
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document.write( "195<BR>\n" );
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