A random sample of n 5 16 scores is selected from a normal population with a mean of m 5 50.

After a treatment is administered to the individuals in the sample, the sample mean is found to be M 5 54.

a. If the population standard deviation is s 5 8, is the sample mean sufficient to conclude that the treatment has a significant effect? Use a two-tailed test with a 5 .05.

b. If the population standard deviation is s 5 12, is the sample mean sufficient to conclude that the treatment has a significant effect? Use a two-tailed test with a 5 .05.

c. Comparing your answers for parts a and

b, explain how the magnitude of the standard deviation influences the outcome of a hypothesis test.