Statistics show on average an adult person receives 425 piec

Statistics show on average an adult person receives 425 pieces of mail each year with a standard deviation of 50.

What are the mean and the standard error of the mean of this sampling distribution if all possible samples of size 100 are selected?.

What is the probability a person chosen at random received less than 475 pieces of mail in a year?

What is the probability the mean of a random sample of 400 persons is more than 415 pieces of mail per year?

mu = 425

sigma = 50

Mean of sample = 425

Std error =425/rt 50 = 60.10

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P(x<475) = P(Z<50/50) = 0.8413

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P(X>415 in the sample) = P(Z>-10/60.10) =

0.3325