Suppose x has a distribution
with a mean of90 and a standard deviation of 36. Random samples of size n = 64
(a) Describe the x distribution
and compute the mean and standard deviation of the distribution.
an approximately normal
distribution with mean μx =
and standard deviation σx =
(b) Find the z value corresponding to x = 81.
(c) Find P(x < 81).
(Round your answer to four decimal places.)
P(x < 81) =
(d) Would it be unusual for a random sample of size 64 from the x distribution to have a sample mean less than 81? Explain.