7. Consider the hypothesis: Ho : s = so He. :s $5 sn where :72 is known. It is known that for detecting a true mean of #1 7E on with probability 1 and type I error or, the required sample size is approximately: n *5 [(Zau + Zak/512 (a) (15 pts) Let us consider that m} : 15 and o2 = 9. If the true mean is 20, what sample size must he used to ensure that the probability of type 11 error is no greater than 0.10? Assume that a: = 0.05. (b) (Bonus question - 15 pts) Derive the expression for n in 7(a)