document.write( "Question 653012: for a normal population mean of 70 and population standard deviation of 20, what is the probability of obtaining a sample mean equal to or greater than 75 for a random sample of n= 100?\r
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\n" ); document.write( "\n" ); document.write( "for a normal population mean of 70 and population standard deviation of 20, what is the probability of obtaining a sample mean equal to or greater than 75 for a random sample of n= 50?\r
\n" ); document.write( "\n" ); document.write( "Please help me solve these
\n" ); document.write( "dbmoody@yahoo.com \n" ); document.write( "
Algebra.Com's Answer #408396 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
for a normal population mean of 70 and population standard deviation of 20, what is the probability of obtaining a sample mean equal to or greater than 75 for a random sample of n= 100?
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\n" ); document.write( "standard deviation for sample means of size 100 is 20/sqrt(100) = 2
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\n" ); document.write( "z(75) = (75-70)/2 = 5/2
\n" ); document.write( "P(x-bar >= 75) = P(z >= 5/2) = normalcdf(5/2,100) = 0.006
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\n" ); document.write( "\n" ); document.write( "for a normal population mean of 70 and population standard deviation of 20, what is the probability of obtaining a sample mean equal to or greater than 75 for a random sample of n= 50?
\n" ); document.write( "std = 20/sqrt(50) = 2.83
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\n" ); document.write( "z(75) = (75-70)/2.83 = 1.77
\n" ); document.write( "P(x-bar >= 75) = P(z >= 1.77) = normalcdf(1.77,100) = 0.038
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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