document.write( "Question 78380: This is a statistics problem, Can someone help? I am so confused.\r
\n" ); document.write( "\n" ); document.write( "An instructor gives a 100 point exam in which the grades are normally distributed. The mean is 60 and the standard deviation is 10. If there are 5% A's and 5% F's, 15% B's and 15% D's and 60% C, find the scores that divide the distribution into those categories \n" ); document.write( "
Algebra.Com's Answer #56223 by stanbon(75887)\"\" \"About 
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An instructor gives a 100 point exam in which the grades are normally distributed. The mean is 60 and the standard deviation is 10. If there are 5% A's and 5% F's, 15% B's and 15% D's and 60% C, find the scores that divide the distribution into those categories.
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\n" ); document.write( "The z-score below which 5% of the scores lie is -1.64485
\n" ); document.write( "The z-score above which 5% of the scores lie is +1.64485
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\n" ); document.write( "Convert these z-scores to raw scores as follows:
\n" ); document.write( "x-60=-1.64485*10
\n" ); document.write( "x=60-16.4485
\n" ); document.write( "x=43.55 (this is the grade score below which 5% of the grades lie)
\n" ); document.write( "-------
\n" ); document.write( "x-60=.64485*10
\n" ); document.write( "x=60+16.4485
\n" ); document.write( "x=76.4485 (this is the grade score above which 5% of the grades lie)
\n" ); document.write( "--------
\n" ); document.write( "Follow the same procedure for the other percentages.
\n" ); document.write( "Let me know if you have trouble with this.
\n" ); document.write( "cheers,
\n" ); document.write( "Stan H.\r
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