Question 3: [14 marks] Part a] (6 marks} Calculate the value of the test statistic, set up the rejection region, undertaking hypothesis test and interpret the result. Ho: Iu, = 19 _ H1: .1! : 19 Given that o' = 5,11 = 25, X = 19.5, a: = 0.05. Part b} {3 marks) A statistics practitioner is in the process of testing to determine whether is enough evidence to infer that the population mean is different from 191]. She calculated the mean and standard deviation of a sample of 200 observations as J? = 180 and s = 20. i) Calculate the value of the test statistic of the test required to determine whether there is enough evidence to infer at the 5% significance level that the population means is diferent from 191}. ii} Repeat the part i} with the population standard deviation to he 20