Question: To test the effectiveness of a treatment, a sample of n=25 people is selected from a normal population with a mean of µ=60. After the treatment is administered to the individuals in the sample, the sample mean is formed to be M=55.

a. If the population standard deviation is ð=10, can you conclude that the treatment has a significant effect? Use a two-tailed test with a ð=.05

b. If the population standard deviation is ð=20, can you conclude that the treatment has a significant effect? Use a two-tailed test with a ð=.05.

c. Compute Cohen’s d to measure effect size for both tests (ð=20 and ð=10).