Vacations Inc. has two telephone operators answering incoming phone calls. In addi- tion, one caller can be put in a waiting line if both operators are busy. If all three lines (two operators plus one waiting line) are busy, the caller gets a busy signal and calls another booking office, so that customer is lost. Calls arrive according to a Poisson process, 15 per hour on average. The length of a call is 4 minutes on average, exponentially distribution. The cost of a phoneline is 0, 20 per hour and the cost of a telephone operator is 9,00 per hour. The average profit on a call is 13,50. The owner of Vacations Inc. is considering getting an extra phoneline and hiring a third telephone operator. a. In the current situation, what percentage of the time is each operator working? b. What is the (long-run) probability that a caller will be lost in the current situation? c. What is the (long-run) probability that a caller will be lost when an additional telephone line is bought and a third operator is hired? d. Do you advice the owner to hire an additional telephone line plus operator or not?