Table provided in pic attached 3A. The water pollution readings at State Park Beach seems to be lower than that of the prior year. A sample of 12 readings (measured in coliform/100 mL) was randomly selected from the records of this year's daily readings. The study yielded the following dista table. table in pic attached

(a) Which approximation is more appropriate in this problem, : ort? Be sure to justify your response. (5 points)
(b) Estimate the 95% upper confidence bound of this year's mean pollution reading. Be sure to justify all steps graphically and analytically. (10 points)

3B. Does the sample study of Problem 3A provide sufficient evidence to conclude that the mean of this year's pollution readings is significantly lower than last year's mean of 3.802?
(c) Set up the appropriate hypotheses. (5 points)
(d) Test the hypotheses with the significance level of a = 0.05. Be sure to justify all steps graphically and analytically. (10 points)