20. A researcher plans to conduct an experiment evaluating the effect of a treatment.  A sample of n = 9 participants is selected and each person receives the treatment before being tested on a standardized dexterity task. The treatment is expected to lower scores on the test by an average of 30 points.  For the regular pollution, scores on the dexterity task form a normal distribution with u = 240 and o = 30. (Show all your work)

a. If the researcher uses a two-tailed test with a = .05, what is the power of the hypothesis test?

b. Ahain assuming a two-tailed test with a = .05, what is the power of the hypothesis test if the sample size is increased to n 25?