1) Make a check sheet and then a Pareto diagram for the following car repair shop data:
|
Ticket No.
|
Work
|
Ticket No.
|
Work
|
Ticket No.
|
Work
|
|
1
|
Tires
|
11
|
Brakes
|
21
|
Lube & oil
|
|
2
|
Lube & oil
|
12
|
Lube & oil
|
22
|
Brakes
|
|
3
|
Tires
|
13
|
Battery
|
23
|
Transmission
|
|
4
|
Battery
|
14
|
Lube & oil
|
24
|
Brakes
|
|
5
|
Lube & oil
|
15
|
Lube & oil
|
25
|
Lube & oil
|
|
6
|
Lube & oil
|
16
|
Tires
|
26
|
Battery
|
|
7
|
Lube & oil
|
17
|
Lube & oil
|
27
|
Lube & oil
|
|
8
|
Brakes
|
18
|
Brakes
|
28
|
Battery
|
|
3
|
Lube & oil
|
19
|
Tires
|
29
|
Brakes
|
|
10
|
Tires
|
20
|
Brakes
|
30
|
Tires
|
2) Prepare a scatter diagram for each of these data sets and then express in words the apparent relationship between the two variables. Put the first variable on the horizontal axis and the second variable on the vertical axis.
|
Age
|
24
|
30
|
22
|
25
|
33
|
27
|
36
|
58
|
37
|
47
|
54
|
28
|
42
|
55
|
|
Absenteeism Rate
|
6
|
5
|
7
|
6
|
4
|
5
|
4
|
1
|
3
|
2
|
2
|
5
|
3
|
1
|
|
Temprature (oF)
|
65
|
63
|
72
|
66
|
82
|
58
|
75
|
86
|
77
|
65
|
79
|
|
Error Rate
|
1
|
2
|
0
|
0
|
3
|
3
|
1
|
5
|
2
|
1
|
3
|
3) An automatic filling machine is used to fill 1-liter bottles of cola. The machine's output is approximately normal with a mean of 1.0 liter and a standard deviation of .01 liter. Output is monitored using means of samples of 25 observations.
a. Determine upper and lower control limits that will include roughly 97 percent of the sample means when the process is in control.
b. Given these sample means: 1.005, 1.001, .998, 1.002, .995, and .999, is the process in control?
4) After a number of complaints about its directory assistance, a telephone company examined samples of calls to determine the frequency of wrong numbers given to callers. Each sample consisted of 100 calls. Determine 95 percent limits. Is the process stable (i.e., in control)? Explain.
SAMPLE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Number of errors 5 3 5 7 4 6 8 4 5 9 3 4 5 6
5) A manager wants to assign tasks to workstations as efficiently as possible and achieve an hourly output of 33Y3 units. Assume the shop works a 60-minute hour. Assign the tasks shown in the accompanying precedence diagram (times are in minutes) to workstations using the following rules:
a. In order of most following tasks. Tiebreaker: greatest positional weight.
b. In order of greatest positional weight. Tiebreaker: most following tasks.
c. What is the efficiency?
6) Determine the placement of departments for a newly designed facility that will minimize total transportation costs using the data in the following tables. Assume that reverse distances are the same. The locations are shown in the grid. Use a cost of $1 per trip yard.
7) A firm has a training program for a certain operation. The progress of trainees is carefully monitored. An established standard requires a trainee to be able to complete the sixth repetition of the operation in six hours or less. Those who are unable to do this are assigned to other jobs.
Currently, three trainees have each completed two repetitions. Trainee A had times of 9 hours for the first and 8 hours for the second repetition; trainee B had times of 10 hours and 8 hours for the first and second repetitions; and trainee C had times of 12 hours and 9 hours. Which trainee(s) do you think will make the standard? Explain your reasoning.
8) A manager wants to estimate the remaining time that will be needed to complete a five-unit job. The initial unit of the job required 12 hours, and the work has a learning percentage of 77. Estimate the total time remaining to complete the job.
9) Kara is supposed to have a learning percentage of 82. Times for the first four units were 30.5, 28.4, 27.2, and 27.0 minutes. Does a learning percentage of 82 seem reasonable? Justify your answer using appropriate calculations.