11. The drug Diffusin is used to treat arthritis pain, and was recently examined in a study of its effect on glaucoma. Ten patients took part in the study, and, for each patient, the change in intraocular pressure (after - before drug administration) was measured in mmHg. For these 10 patients the average change was -1.6 mmHg, with an estimated standard deviation of 1.5 mmHg.

(a) Using a two-sided hypothesis test, assess the evidence for the claim that this drug changes intraocular pressure on the eye. Be sure that all the steps in testing are clearly indicated in your solution. Use alpha = 0.05. Assume that the conditions required for the test are met. (10 points).

(b) Based on the results of this hypothesis test, would you expect a confidence interval to include 0? Explain your reasoning. (5 points).

(c) Calculate a 95% confidence interval for the change in pressure. Does the confidence interval provide convincing evidence that this drug changes intraocular pressure on the eye? Explain. (10 points)