standard deviation
Question
Suppose x has a distribution
with a mean of 90 and a standard deviation of 36. Random samples of size n = 64
are drawn.
(a) Describe the x distribution
and compute the mean and standard deviation of the distribution.
x
has
—Select—
an approximately normal
a Poisson
an unknown
a geometric
a binomial
a normal
distribution with mean μx =
and standard deviation σx =
.
(b) Find the z value corresponding to x = 81.
z =
(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.