The mean of nonresidential buildings is 30 years and the standard deviation of the ages of the buildings is 5 years. Determine the probability that a random sample of a group of 50 nonresidential buildings will have a mean age of less than 27.5 years.

Question

The mean of nonresidential buildings is 30 years and the standard deviation of the ages of the buildings is 5 years.  Determine the probability that a random sample of a group of 50 nonresidential buildings will have a mean age of less than 27.5 years.

PsyDAG · Answer

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.