Question 1062009
One-tailed test.  You are interested in one side of the difference, not just whether there is a difference.
Reject when z>1.645, which is the one-sided 95th percentile.
The test stat is z(0.95)=(x bar-mean)/sigma/sqrt(48)
=(22-21)*sqrt (48)/6
=1*6.928/6=1.16
Fail to reject the null hypothesis.  Insufficient evidence to state that the mean is greater than 21.
p=0.1241, from table or calculator.