[BUS002] Operations Management Dr Eun-Seok Kim
1
Individual Report (80%)
In this report, you are required to answer ALL FIVE QUESTIONS. Your answers are to be presented in a single report format, and in answering these questions, please
• state and explain all assumptions, on which your answers are based;
• support any answers with the appropriate calculations to arrive at the answer.
While each individual answer might have a different word count from the others, the overall word count should not exceed 2,000 (+ or – 10%) words excluding calculations (numbers and equations, etc.). The report in PDF FORMAT ONLY should be submitted via QMplus by Friday, 13th December 2019 at 11.55 PM. Late submissions will be penalised according to School regulations. Under no circumstances can submissions via email be accepted. Under no circumstances should you attempt to hand in your work directly to the lecturer or to the class teacher.
In any case you are affected by EXTENUATING CIRCUMSTANCES that might prevent you from submitting your work on time, you should contact the module organiser (Dr. Eun-Seok Kim, e.kim@qmul.ac.uk) AND student support officer (Ms Ripa Parvin, r.parvin@qmul.ac.uk) as soon as possible when the problem occurs and no later than the deadline for submitting the report. Extenuating circumstances will be evaluated in accordance with College regulations.
Q1. (20%) A production operation is making 150 units of a product by engaging five workers for 300 hours. However, 40 percent of the units appear to have various quality problems, and the company decides to sell them as seconds at a price of £50 each when a normal unit is sold for £150. To improve the situation, several initiatives are proposed, including a scheme where, for every improvement, 50 percent will be given to workers and the other 50 percent will be held by the company. This results in a significant drop in defects as now only 10 units are faulty out of an output of 130 units.
a) Compare the productivity after Bonus with the initial productivity. (10%)
b) Determine the appropriate bonus per hour for the workers under the bonus scheme if the cost per piece is £70 both before and after the scheme. (10%)
[BUS002] Operations Management Dr Eun-Seok Kim
2
Q2. (20%) As the Cottrell Bicycle Co. of St. Louis completes plans for its new assembly line, it identifies 25 different tasks in the production process. VP of Operations Jonathan Cottrell now faces the job of balancing the line. He lists precedences and provides time estimates for each step based on work-sampling techniques. His goal is to produce 1,000 bicycles per standard 40-hour workweek.
Task Time (sec) Immediate Predecessors Task Time (sec) Immediate Predecessors
K3
60
–
E3
109
F3
K4
24
K3
D6
53
F4
K9
27
K3
D7
72
F9, E2, E3
J1
66
K3
D8
78
E3, D6
J2
22
K3
D9
37
D6
J3
3
–
C1
78
F7
G4
79
K4, K9
B3
72
D7, D8, D9, C1
G5
29
K9, J1
B5
108
C1
F3
32
J2
B7
18
B3
F4
92
J2
A1
52
B5
F7
21
J3
A2
72
B5
F9
126
G4
A3
114
B7, A1, A2
E2
18
G5, F3
a) Balance this operation using shortest operation time rule and compute the efficiency of the line. (10%)
b) Discuss how this balance could be improved. Is it possible to improve this balance to 100%? (10%)
[BUS002] Operations Management Dr Eun-Seok Kim
3
Q3. (20%) Thomas Smith is the purchasing manager for the headquarters of a large insurance company chain with a central inventory operation. Thomas’s fastest-moving inventory item has a daily demand of 24 units. The cost of each unit is £100, and the inventory carrying cost is £10 per unit per year. The average ordering cost is £30 per order. It takes about 5 days for an order to arrive, and there are 250 working days per year.
a) To minimize the cost, how many units should be ordered each time an order is placed? What is the total annual inventory cost, including the cost of the units? (10%)
b) Even if there is substantial uncertainty in the parameters in the EOQ-model, it is still quite a useful model. Discuss why. (10%)
Q4. (20%) Emery Pharmaceutical uses an unstable chemical compound that must be kept in an environment where both temperature and humidity can be controlled. Emery uses 200 pounds per month of the chemical, estimates the holding cost to be £3.33 (because of spoilage), and estimates order costs to be £10 per order. The cost schedules of four suppliers are as follows: Vendor 1 Vendor 2 Quantity Price/LB (£) Quantity Price/LB (£)
1-49
35.00
1-74
34.75
50-74
34.75
75-149
34.00
75-149
33.55
150-299
32.80
150-299
32.35
300-499
31.60
300-499
31.15
500+
30.50
500+
30.75
Vendor 3 Vendor 4 Quantity Price/LB (£) Quantity Price/LB (£)
1-99
34.50
1-199
34.25
100-199
33.75
200-399
33.00
200-399
32.50
400+
31.00
400+
31.10
a) What quantity should be ordered, and which supplier should be used? (10%)
b) Discuss factor(s) should be considered besides total cost. (10%)
[BUS002] Operations Management Dr Eun-Seok Kim
4
Q5. (20%) A process considered to be in control measures an ingredient in ounces. A quality inspector took 10 samples, each with 5 observations as follows: Samples Observations 1 2 3 4 5 1
10
9
10
9
12 2
9
9
11
11
10 3
13
9
10
10
9 4
10
10
11
10
10 5
12
10
9
11
10 6
10
10
8
12
9 7
10
11
10
8
9 8
13
10
8
10
8 9
8
8
12
12
9 10
10
12
9
8
12
a) Using this information, obtain three-sigma (i.e., z=3) control limits for a mean control chart and control limits for a range chart, respectively. It is known from previous experience that the standard deviation of the process is 1.36. (10%)
b) Discuss whether the process is in control or not. (10%)