Bart Simpson, a manager of janitorial services at Wombat University, must schedule the regular maintenance by his janitorial engineers. There are two crews: sweeping crew and waxing crew. Union rules prohibit sweepers from waxing and waxers from sweeping. A building’s floors must first be swept before they can be waxed. Bart must schedule the order in which maintenance crews will visit each of Wombat U’s five buildings. Times required to sweep and wax each building are as follows:

Sweeping (Hours) Waxing (Hours)

(A)stronomy 2 2

(B)iology 4 1

(C)hemistry 5 5

(D)rama 3 2

(E)nglish 1 2

a. What schedule produces the shortest time span in which these orders can be completed? What is the sequence of order?

b. How many hours does it take to complete the five orders?

c. For the schedule in question a, how many hours is the waxing task idle?

d. How many hours jobs waiting for the waxing task?

e. What is the average order completion time?