Question 447271
When a production process is operating correctly, the number of units produced per hour has a normal distribution with a mean of 100 and standard deviation of 10. A random sample of 4 hours was taken. Complete parts (a) through (d)
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a. Find the mean of the sampling distribution of the sample means.
mean of the sample means = 100
std of the sample means = 10/sqrt(4) = 5
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b. Find variance
var of the sample means = 5^2 = 25
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c. Find standard error
10/sqrt(2)
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d. What is the probability the sample mean exceeds 101.2?
t(101.2) = (101.2-100)/[10/sqrt(4)] = 1.2/5 = 0.24
P(x-bar > 101.2) = P(t > 0.24 when df = 3) = 0.4129
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Cheers,
Stan H. 
thanks alot.. if you won't answer all, just parts of it will do because i need a guide to start the question, and then maybe i can just flow through.. :)