(a) A typist at an office receives, on an average, 22 letters per day of typing. The typist works 8 hours a day and it takes on an average 20 minutes to type a letter. The company has determined that the cost of a letter waiting to be mailed (opportunity cost) is 80 paise per hour and the equipment operating cost plus the salary of the typist will be Rs 40 per day.

(i) What is the typist's utilisation rate?

(ii) What is the average number of letters waiting to be typed?

(iii) What is the average waiting time needed to have a letter typed?

(iv) What is the total cost of waiting letters to be mailed?