The mean age of all the inmates at Concord Prison is 22 with a standard deviation of 7.5.

A recent survey by a hostile researcher makes damaging criticisms of the educational standards in the prison. The prison warden suspects that the 100 prisoners interviewed for the study were not chosen at random.

The mean age of the prisoners chosen was 20. Can the warden use this finding to cast doubt upon the sampling method of the survey?

(Hint: Test to see if there is a significant age difference [either positive or negative, i.e., two-tailed] between the sample of prisoners and the total population of prisoners). Use an alpha of .01 and outline each of the stages of a hypothesis test along the way.

State all steps in hypothesis testing.