document.write( "Question 1196667: IF A SAMPLE OF 30 MEN IS SELECTTED WHAT IS THE 90TH PERCENTILE OF THE MEAN NUMBER OF CUPS PER DAY
\n" ); document.write( "MEAN IS 3.8
\n" ); document.write( "SD 0.7
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Algebra.Com's Answer #829668 by Theo(13342)\"\" \"About 
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mean is 3.8
\n" ); document.write( "standard deviation is .7
\n" ); document.write( "sample size is 30
\n" ); document.write( "standard error is .7/sqrt(30) = .1278
\n" ); document.write( "t-score formula is t = (x - m) / s
\n" ); document.write( "t is the t-score
\n" ); document.write( "x is the raw score
\n" ); document.write( "m is the mean
\n" ); document.write( "s is the standard error if you are looking for the mean of multiple samples of size 30.
\n" ); document.write( "the 90th percentile for a t-score with 29 degrees of freedom (sample size minus 1), is equal to 1.3114
\n" ); document.write( "t-score formula becomes 1.3114 = (x - 3.8) / .1278.
\n" ); document.write( "solve for x to get:
\n" ); document.write( "x = 1.3114 * .1278 + 3.8 = 3.9676
\n" ); document.write( "90 percent of the means of samples of size 30 will be less than 3.9676.
\n" ); document.write( "that's your 90th percentile.
\n" ); document.write( "here's what it looks like on a graph.
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