b) Let X1, X2...., Xn be a random sample of size n = 30 from a normal distribution with mean, 0 and variance. . We wish to test Ho : ,6 = 20 versus H1 : = 25. where 131 > 130- n (i) Show that the best critical region for the test is 2x52 2 c . (8 marks) i=1 (ii) Estimate the probability of committing Type Ii error. (4 marks) (iii) Find the best critical region for the test so that a = 0.05. (4 marks)