he quantity of a particular pollution element in a city A, registered with the right unit of measure, follows a Normal distribution with expected value and variance = 4 . If the actual average quantity is more than 7.5, some anti-pollution measure must be taken. In a sample of 10 measure stations in this city, the mean is 8.2.

a) What decision would you make about anti-pollution actions, using a level of significance =0.05? (z0.05= 1.645)

b)Calculate the probability of Type II error, assuming a true value of = 8.