# can anyone help me with this problem?

a sample of n=9 indivividuals was selected from a normally distributed pop. with a mean of M=25 and a standard deviation of 6.a treatment was administered to the sample, and treatment , the nine individuals produced the following score: 36,27,30,33,22,30,30,24,38

-use a hypothesis test with alpha=.05 to determine whether the treatment had a significant effect. the value for Z in this instant is?

this is what i did:

-i calculated the mean for the sample, which was 30.

-then i used the formula 30-25/2=2.5

-the critical value(two-tailed, alpha .05) for Z in this instance is +/- 1.96

is this correct?