document.write( "Question 677074: 40 students scored 70 on a test the standard deviation is 5.5 if the test of 10 students are picked randomly what is the probability their mean is greater than 77
\n" ); document.write( "& what is their probabilty their mean is less than 77 \n" ); document.write( "

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40 students scored 70 on a test the standard deviation is 5.5 if the test of 10 students are picked randomly what is the probability their mean is greater than 77
\n" ); document.write( "& what is their probabilty their mean is less than 77
\n" ); document.write( "------
\n" ); document.write( "Using population size = 40 and pop. std = 5.5,
\n" ); document.write( "pop mean = np = 70
\n" ); document.write( "----
\n" ); document.write( "For all samples of size 10, the mean of the sample means is 70
\n" ); document.write( "and the std is 5.5/sqrt(10)
\n" ); document.write( "-----
\n" ); document.write( "Problem:
\n" ); document.write( "z(77) = (77-70)/(5.5/sqrt(10)) = 1.7393
\n" ); document.write( "p(x-bar > 77) = normalcdf(1.7303,100) = 0.0410
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\n" ); document.write( "p(x-bar < 77) = 1 - 0.0410 = 0.9590
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "

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