document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=348892>Question 348892</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am having a hard time in my Biostatistics class. I don't understand anything about it.Need someone to explain how to figure this out so i can complete the other questions.<BR>\n" );
document.write( "Total cholesterol in children ages 10 to 15 years of age is assumed to follow a normal distribution with a mean of 191 and a standard deviation of 22.4.<BR>\n" );
document.write( "a. What proportion of children 10 to 15 have a total cholesterol between 180 and 190?<BR>\n" );
document.write( "b. What proportion of children 10 to 15 would be classified as hyperlipidemic(assume that hyperlipidemia is defined as a total cholesterol level over 200?<BR>\n" );
document.write( "c. what is the 90th percentile of total cholesterol? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #249406 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=249406\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Total cholesterol in children ages 10 to 15 years of age is assumed to follow a normal distribution with a mean of 191 and a standard deviation of 22.4.<BR>\n" );
document.write( "a. What proportion of children 10 to 15 have a total cholesterol between 180 and 190?<BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "Find the z-scores:<BR>\n" );
document.write( "z(180) = (180-191)/22.4 = -0.4911<BR>\n" );
document.write( "z(190) = (190-191)/22.4 = -0.0446<BR>\n" );
document.write( "----<BR>\n" );
document.write( "The proportion between 180 and 190 = the probability<BR>\n" );
document.write( "that z is between -0.4911 and -0.0446 = 17.05%<BR>\n" );
document.write( "------------------------------------------------------\r<BR>\n" );
document.write( "\n" );
document.write( "b. What proportion of children 10 to 15 would be classified as hyperlipidemic(assume that hyperlipidemia is defined as a total cholesterol level over 200?<BR>\n" );
document.write( "---<BR>\n" );
document.write( "z(200) = (200-191)/22.4 = 0.4018<BR>\n" );
document.write( "Proportion over 200 = probability z is greater than 0.4018 = 34.49%<BR>\n" );
document.write( "-------------------------------------------------------\r<BR>\n" );
document.write( "\n" );
document.write( "c. what is the 90th percentile of total cholesterol?<BR>\n" );
document.write( "Find the z-value corresponding to a left-tail of 0.90.<BR>\n" );
document.write( "---<BR>\n" );
document.write( "invNorm(0.90) = 1.2816<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Use x = zs+u to find the total cholesterol.<BR>\n" );
document.write( "x = 1.2816*22.4+191 = 219.71<BR>\n" );
document.write( "==================================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );