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 each Z score.
From that, you should be able to decide whether or not it is unusual.
Assume that a population is normally distributed with a mean of 100 and a standard deviation of 15. Would it be unusual for the mean of a sample of 3 to be 115 or more? Why or why not?
What if the size for each sample was increased to 20? Would a sample mean of 115 or more be considered unusual? Why or why not?
1 answer
1 answer