SOLUTION: a population of normally distributed test scores has mean of 72 and standard deviation of 13. If 25 test scores are randomly selected, what is the probability the average score is

Question 917405: a population of normally distributed test scores has mean of 72 and standard deviation of 13. If 25 test scores are randomly selected, what is the probability the average score is under 75
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
a population of normally distributed test scores has mean of 72 and standard deviation of 13. If 25 test scores are randomly selected, what is the probability the average score is under 75
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t(75) = (75-72)/[13/sqrt(25)] = 3/(13/5) = 15/13
P(x < 75) = P(t < 15/13) = tcdf(-100,15/13,24) = 0.87
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Cheers,
Stan H.
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