2. (6 marks) A quality control expert monitors the size of precision parts coming off a production line to make sure that the (true) standard deviation of the dimension of the parts does not exceed 2 millimetres. She will halt production if, on the basis of the latest sample taken, she is 95% sure that the (true) standard deviation is greater than 2 millimetres. (Clearly, she has an a = 0.05 chance of being wrong). A random sample of 20 parts produced a standard deviation of 2.82 millimetres. Will she halt production? YES/NO?-You must perform an appropriate hypothesis test to decide. You may assume that the sizes of the parts are normally distributed