document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=835668>Question 835668</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A statistics teacher believes that the final exam grades for her elementary statistics class have a normal distribution with a mean of 82 and a standard deviation of 8.<BR>\n" );
document.write( "a. Find the score which separates the top 10% of the scores from the lowest 90% of the scores.<BR>\n" );
document.write( "b. The teacher plans to give all students who score in the top 10% of scores an A. will a student who scored a 90 on the exam receive an A? Explain.<BR>\n" );
document.write( "c. Find the score which separates the lowest 20% of the scores from the highest 80% of the scores.<BR>\n" );
document.write( "d. The teacher plans to give all students who scores in the lowers 10% of scores an F. will a student who scored 65 on the exam receive F? Explain </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #503659 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=503659\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A statistics teacher believes that the final exam grades for her elementary statistics class have a normal distribution with a mean of 82 and a standard deviation of 8.<BR>\n" );
document.write( "a. Find the score which separates the top 10% of the scores from the lowest 90% of the scores.<BR>\n" );
document.write( "Find the z-value with a right tail of 10%<BR>\n" );
document.write( "invNorm(0.90) = 1.2816<BR>\n" );
document.write( "Find the corresponding raw score::<BR>\n" );
document.write( "x = 1.2816*8+82 = 92.25<BR>\n" );
document.write( "------------------------------------------<BR>\n" );
document.write( "b. The teacher plans to give all students who score in the top 10% of scores an A. will a student who scored a 90 on the exam receive an A? Explain.<BR>\n" );
document.write( "Ans: No; the student needs a score of at leasst 92.25<BR>\n" );
document.write( "---------------------------<BR>\n" );
document.write( "c. Find the score which separates the lowest 20% of the scores from the highest 80% of the scores.<BR>\n" );
document.write( "z-score for left-tail of 20% = invNorm(0.20) = -0.8416<BR>\n" );
document.write( "x = -0.8416*8+82 = 75.27<BR>\n" );
document.write( "-------------------------------------<BR>\n" );
document.write( "d. The teacher plans to give all students who scores in the lowers 10% of scores an F. will a student who scored 65 on the exam receive F? Explain<BR>\n" );
document.write( "z-score = invNorm(0.10) = -1.2816<BR>\n" );
document.write( "Top score in lower 10% = -1.2816*8+82 = 71.74<BR>\n" );
document.write( "A student with a 65 would get an F because 65 < 71.74<BR>\n" );
document.write( "=================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "================<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );