Question 3 [12 marks]

Jack Computers sells and services several brands of computer. Based on sales record of a particular brand of computer the following probability distribution for demand is obtained

Demand per week	Probability
0	0.1
1	0.15
2	0.25
3	0.2
4	0.1
5	0.2

Based on cost consideration, Jack Computers decided to order 9 of these each time an order is placed. The holding cost is RM5 per week for each that is left in inventory at the end of the week. The stockout cost has been set as RM55 per stockout. Jack Computers has decided to place an order whenever there only three computers left in inventory. The lead-time in weeks is described by the following distribution

Lead time (weeks)	Probability
1	0.1
2	0.45
3	0.25
4	0.2

Currently there are 3 computers in inventory. Simulate 20 weeks operation for Jack Computers Determine the average inventory cost and average stockout cost.

Question 4 [13 marks]

Shan owns a petrol station. The cars arrive at the petrol station according to the following interarrival-time distribution. The time to service a car is given by the following service-time distribution. Simulate the arrival and service times of 15 cars at the petrol station. Estimate the average customer waiting time, average service time and average time a car spends in the system.

Interarrival Time (Minutes)	Probability
4 8 15 20	0.35 0.25 0.30 0.10

Service Time (Minutes)	Probability
2 4 6 8	0.30 0.40 0.20 0.10