Suppose that Y1, Y2,..., Y20 N(u, 5), and that you want to test Ho u = 7 versus Ha : u >7, using the test based on X analogous to the example discussed in lecture, at significance level a = 0.05. Note that o2 = 5 is known here. Find the smallest sample size such that the power of this test is at least 0.80, when u = 8.