(a) An operator for a telephone-answering service answers a large number of calls for two real estate agents. The two agents are charged the same monthly fee for this service and it is assumed that they will each receive approximately half the calls coming in. Based on this assumption, find the probability that in the next 150 calls 90 or more will be for one agent. (Use normal approximation of the binomial distribution.)

(b) It is found that 60% of Australians who exercise daily by walking are women. A randomly selected group comprises of 15 people who exercise daily, with certain number of women in the group. What is the approximate probability that there will be an exactly 11 females in the group?

(c) A survey of 500 engineers found that 60 of them indicated that they were unhappy with their present work environment. A similar study conducted 3 years ago found that 8% of engineers were unhappy. The following hypotheses were established:

Ho : p = 0.08

H1 : p ? 0.08