Operations Management exam

Question 1

A single machine work center has five jobs assigned to it. They are labeled, in the order of their arrival in the shop, as jobs A, B, C, D and E. The work center may work on only one job at a time and must complete any job it starts before starting another job. Job A has a processing time of 6 days and is due to the customer in 9 days. Job B has a processing time of 2 days and is due in 16 days. Job C has a processing time of 4 days and is due in 10 days. Job D has a processing time of 3 days and is due in 7 days. Job E has a processing time of 5 days and is due in 12 days. Using the first-come-first-served priority rule, what is the number of late (tardy) jobs?

Answer

		0 (zero)
		1
		2
		3
		4

5 points

Question 2

A single machine work center has five jobs assigned to it. They are labeled, in the order of their arrival in the shop, as jobs A, B, C, D and E. The work center may work on only one job at a time and must complete any job it starts before starting another job. Job A has a processing time of 6 days and is due to the customer in 9 days. Job B has a processing time of 2 days and is due in 16 days. Job C has a processing time of 4 days and is due in 10 days. Job D has a processing time of 3 days and is due in 7 days. Job E has a processing time of 5 days and is due in 12 days. Using the shortest (earliest) due date rule, what is the average completion (flow) time of all jobs?

Answer

		4.0
		12.6
		2.6

5 points

Question 3

A single machine work center has five jobs assigned to it. They are labeled, in the order of their arrival in the shop, as jobs A, B, C, D and E. The work center may work on only one job at a time and must complete any job it starts before starting another job. Job A has a processing time of 6 days and is due to the customer in 9 days. Job B has a processing time of 2 days and is due in 16 days. Job C has a processing time of 4 days and is due in 10 days. Job D has a processing time of 3 days and is due in 7 days. Job E has a processing time of 5 days and is due in 12 days. Using the shortest processing (operating) time priority rule, what will be the average tardiness of these orders?

Answer

		2.6
		2.0
		3.0

5 points

Question 4

A single machine work center has five jobs assigned to it. They are labeled, in the order of their arrival in the shop, as jobs A, B, C, D and E. The work center may work on only one job at a time and must complete any job it starts before starting another job. Job A has a processing time of 6 days and is due to the customer in 9 days. Job B has a processing time of 2 days and is due in 16 days. Job C has a processing time of 4 days and is due in 10 days. Job D has a processing time of 3 days and is due in 7 days. Job E has a processing time of 5 days and is due in 12 days. Using the shortest processing (operating) time priority rule, what will be the average number of jobs in the system?

Answer

		5
		4
		3
		2.5

5 points

Question 5

A machine shop has two machines, M1 and M2. Four jobs A, B, C, and D need to be processed through machines M1 first and M2 second. Job A will take one hour on machine M1 and three hours on machine M2. Job B will take three hours on M1 and two hours on M2. Job C, takes seven hours on M1and three hours on M2. Job D, requires five hours on M1 and one hour on M2. Using Johnson's rule, in what order should these jobs be done? Select one of the following answers.

Answer

		ABCD
		ACBD
		DABC
		DACB

5 points

Question 6

Consider the following data for a five-job, 2-machine, flow-shop problem. Find the value of make-span (minimum time to complete all jobs) using the sequence ABCDE. (Note: It is suggested that you draw the Gantt chart first.)

	Time	Time
Job	M1	M2
A	1	2
B	4	2
C	1	3
D	5	4
E	3	5

Answer

		16
		19
		20
		30

5 points

Question 7

Which of the following is a measure of whether the job is done ahead of, on, or behind schedule?

Answer

		average number of jobs in system
		mean flow time
		makespan
		job tardiness
		job lateness

5 points

Question 8

Suppose SPT rule is being used in a "dynamic" scheduling problem. There are five jobs A,B,C,D, and E ready to be processed at the present time. The processing times for the five jobs are 1, 9, 7, 2, and 6 days respectively. A new job F will arrive on the 8th day. The processing time for job F is 5 days. On which day (from present time) job F will be completed?

Answer

		25
		14
		13
		5

5 points

Question 9

Johnson's rule gives the optimal answer for which of the following type of problems?

Answer

		Minimize make span in a two machine flow shop
		Minimize make span in a two machine job shop
		Minimize make span in a single machine problem
		Minimize make span in both two machine flow and job shops.

5 points

Question 10

Which scheduling rule will minimize the average number of jobs in a single machine scheduling problem?

Answer

		First Come First Served (FCFS)
		Earliest Due Date (EDD)
		Shortest Processing Time (SPT)
		Does not matter which rule you use. All rules will give the same answer.

5 points

Question 11

Use the data given in the following table and the relationships between activities shown in the Activity on Node (AON) network. Find the project duration (earliest completion time of the project).

Activity	A	B	C	D	E	F	G
Time (days)	5	6	9	4	9	3	4

Answer

		21
		22
		25
		28
		31

5 points

Question 12

Use the data given in the following table and the relationships between activities shown in the Activity on Node (AON) network. What is the latest start time of activity C if the project completion time (due date) is set at 33 day?

Activity	A	B	C	D	E	F	G
Time (days)	5	6	9	4	9	3	4

Answer

		5
		7
		33
		Zero (0)

5 points

Question 13

The data for a Time-Cost CPM Scheduling model analysis are given below. The times are in days. What is the minimum cost to complete this project in 14 days? (Hint: This problem requires crashing).

Activity	Immediate Predecessor	Normal Time	Crash Time	Normal Cost ($)	Crash Cost ($)
A	None	4	2	2000	4000
B	A	4	3	3000	6000
C	A	2	1	2000	2500
D	B and C	4	2	5000	5600
E	D	3	1	6000	9000

Answer

		18,000
		27,100
		18,300
		300

5 points

Question 14

You are working on a project that has 12 activities. You determine that the critical path consists of only five activities. You then compute the variances for the five critical path activities and these variances are 3, 4, 2, 1, and 6 days. The desired completion date for the project is 44 days and the expected completion date for the project is 40 days. Which of the following alternatives gives the probability that the project will be completed by the desired completion date?

Answer

		Close to 1.0
		Close to 0.3413
		Close to 0.8413
		Close to 0.5987
		Close to 0.0987

5 points

Question 15

Suppose the length of critical path in a project is 50 days. The probability of completing the project within 50 days is:

Answer

		Less than 50%
		Greater than 50%
		Equal to 50%
		Can not be determined from the above data

5 points

Question 16

Suppose the length of critical path in a project is 40 days and the standard deviation is 2 days. What due date should be set for the project so that the probability of completing the project is 95%? Round the answer to the nearest higher integer.

Answer

		40
		41
		44
		45

5 points

Question 17

The longest path in a network is called the critical path. Is it possible to have more than one critical path in a network?

Answer

		yes
		no

5 points

Question 18

You have collected the data for a Time-Cost CPM Scheduling model analysis. The time is in days and the project "direct costs" are given below.
The indirect costs for the project are determined on a daily duration basis and are given below:

Activity	Immediate Predecessor	Normal Time (days)	Crash Time (days)	Normal Cost ($)	Crash Cost ($)
A	None	3	2	300	400
B	A	3	3	100	100
C	A	1	1	200	200
D	B and C	3	2	400	550
E	D	2	1	500	900
F	E	3	3	200	200
G	F	2	2	100	100

Total indirect costs for 16 days of project duration: $ 600
Total indirect costs for 15 days of project duration: $ 400
Total indirect costs for 14 days of project duration: $ 200
Total indirect costs for 13 days of project duration: $ 100
At what project duration do we achieve the lowest total project cost (i.e., direct plus indirect costs)?

Answer

		16 days
		15 days
		14 days
		13 days

5 points

Question 19

Consider a project having the following ten activities. What is the critical path?

Activity	A	B	C	D	E	F	G	H	I	J
Immediate Predecessor	None	None	A	A, B	C, D	D	C	E, G	E, F	H, I
Time (weeks)	7	3	5	6	4	4	9	8	6	5

Answer

		A-C-G-H-J
		A-B-C-D-E-F-G-H-I-J
		A-D-E-H-J
		B-D-F-I-J

5 points

Question 20

Consider a project having the following ten activities. What is the slack time of activity B?

Activity	A	B	C	D	E	F	G	H	I	J
Immediate Predecessor	None	None	A	A, B	C, D	D	C	E, G	E, F	H, I
Time (weeks)	7	3	5	6	4	4	9	8	6	5

Answer

		zero
		8
		11
		3
		19