The average teacher's salary in North Dakota is $41,027. Assume a normal distribution with standard deviation of $5200.

A. what is the probability that a randomly selected teachers salary is less than 40,000?

B. What is the probability that the mean for a sample of 80 teachers' salaries is greater than 42,000

1 answer

A. Use same process as previous post.

B. Now we are talking about a distribution of means rather than raw scores.

Z = (score-mean)/SEm

SEm = SD/√n

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.