SOLUTION: 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 & what is their

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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
& what is their probabilty their mean is less than 77
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
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
& what is their probabilty their mean is less than 77
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Using population size = 40 and pop. std = 5.5,
pop mean = np = 70
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For all samples of size 10, the mean of the sample means is 70
and the std is 5.5/sqrt(10)
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Problem:
z(77) = (77-70)/(5.5/sqrt(10)) = 1.7393
p(x-bar > 77) = normalcdf(1.7303,100) = 0.0410
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p(x-bar < 77) = 1 - 0.0410 = 0.9590
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Cheers,
Stan H.