A typist at an office of a company receives on the average 20 letters per day for typing. The typist works 8 hours a day and it takes on the average 20 minutes to type a letter. The cost of a letter waiting to be mailed (opportunity cost) is 75 cents per hour and the cost of the equipment plus salary of the typist is $45 per day.
a) What is the typist's utilization rate?
b) What is the average number of letters waiting to be typed?
c) What is average waiting time needed to have a letter typed?
d) What is the total daily cost of waiting letters to be mailed?