Question 1077769: 8.1 #5
A simple random sample of size n=12 is obtained from a population with
μ=69 and σ=16.
=
(a) What must be true regarding the distribution of the population in order to use the normal model to compute probabilities involving the sample mean? Assuming that this condition is true, describe the sampling distribution of
x ( with overbar on top of x).
(b) Assuming the normal model can be used, determine P(x<72.2).
(c) Assuming the normal model can be used, determine P(x≥70.7).
I know what A is, μx=69 and σ=16/the square root of 16
I just don't know what b or c are. thank you!
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! z=(72.2-69)/(16/sqrt(12))--not sqrt (16)
=0.6928
probability < 0.6928 is 0.7558.
probability x > 70.7 is z > (1.7)/16/sqrt(12)=0.3680
That probability is 0.3564
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