13 Solutions.pdf

Lesson 13 Introduction to Quality Solutions Solved Problem #1: see textbook The following problems should be done manually and graphs should be to an appropriate scale.

#1: The following is a list of work done by an automobile service shop. Ticket No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 a.

Work Tires Lube & oil Tires Battery Lube & oil Lube & oil Lube & oil Brakes Lube & oil Tires Brakes Lube & oil Battery Lube & oil Lube & oil

Ticket No. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Prepare a check sheet showing the number of times each type of work was performed? Work

# Times

Tires Lube & Oil Battery Brakes Transmission Total

b.

Work Tires Lube & oil Brakes Tires Brakes Lube & oil Brakes Transmission Brakes Lube & oil Battery Lube & oil Battery Brakes Tires

6 12 4 7 1 30

Prepare a Pareto diagram for the type of work performed?

1

Automobile Shop Service Work 14 12 10 8 6 4 2 0 Lube & Oil

Brakes

Tires

Battery

Transmission

#2: An air conditioning repair department manager has compiled data on the primary reason for 41 service calls for the previous week as shown in the table below. Job Number 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321

Problem F O N N W N F N W N N F N W F O W N O F F

Customer Type R R C R C R R C R R R C R C R C C C C R R

Job Number 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341

Problem O F N F O W O O N N W O O N W O O F N O

Customer Type R R C R R C C C R R R R C R R C R R R C

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Key:

N F W O

a.

Problem Type Noisy Equip. Failure Runs warm Odor

C R

Customer Type Commercial customer Residential customer

Prepare a check sheet showing the repair problem type? Problem Type

Noisy Equip. Failure Runs warm Odor Total

b.

# Times

13 9 7 12 41

Prepare a Pareto diagram for the repair problem type? Repair Problem Type 14 12 10 8 6 4 2 0 Noisy

Odor

Equip. Failure

Runs warm

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#3: The number defective by time for a company which produces computer monitors was obtained by an analyst who observed the number of defectives through out the work day. The work day begins at 8:00am and ends at 5:00pm. Workers are given a 15-minute break at 10:15am, and 3:15pm. Lunch is at 12:00noon. The data is in the table below.

Time 8:00 AM 8:15 AM 8:30 AM 8:45 AM 9:00 AM 9:15 AM 9:30 AM 9:45 AM 10:00 AM 10:30 AM 10:45 AM 11:00 AM 11:15 AM 11:30 AM 11:45 AM a.

# Defective 1 0 0 1 0 1 1 2 3 1 0 0 0 1 3

Time 1:00 PM 1:15 PM 1:30 PM 1:45 PM 2:00 PM 2:15 PM 2:30 PM 2:45 PM 3:00 PM 3:30 PM 3:45 PM 4:00 PM 4:15 PM 4:30 PM 4:45 PM

# Defective 1 0 0 1 1 0 2 2 3 0 1 0 0 1 3

Prepare a run chart showing the number of defectives by time? # Defective

3.5 3 2.5 2 1.5 1 0.5 0 8:00 A M

8:45 A M

b.

9:30 A M

10:15 A M

11:00 A M

11:45 A M

12:30 P M

1:15 P M

2:00 P M

2:45 P M

3:30 P M

4:15 P M

5:00 P M

5:45 P M

What can you conclude? Defects are highest just before breaks, lunch, and quitting time.

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#4: In the following table are the calls that were recorded for an emergency 911 call between 1:00am and 2:30am. As you can see more than one call can occur in any given minute. Three operators were on call on this particular night. Call 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

a.

Time 1:03 1:06 1:09 1:11 1:12 1:17 1:21 1:27 1:28 1:29 1:31 1:36 1:39 1:42 1:43 1:44 1:47 1:48 1:50 1:52 1:53

Call 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

Prepare a check sheet showing the number of calls in each 15 minute interval? Time Interval 1:00

1:15

1:15

1:30

1:30

1:45

1:45

2:00

2:00

2:15

2:15

2:30 Total

b.

Time 1:56 1:56 2:00 2:00 2:01 2:02 2:03 2:03 2:04 2:06 2:07 2:08 2:08 2:11 2:12 2:12 2:13 2:14 2:14 2:16 2:19

# Calls

5 5 6 9 15 2 42

Based on this information, do you feel the three operators were sufficient to handle the call volume? There were 15 calls between 2:00am and 2:15. If the length of each call was more than 3 minutes each, then the 3 operators would have been insufficient to answer the calls in a timely manner.

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#5: Prepare a simple cause-and-effect (Ishikawa) diagram to analyze the possible causes for a table lamp fails when turned on.

#6: The human resources manager wants to determine if there is a relationship between age and absenteeism. She takes a random sample of several employees with different ages and records their absences. The sample results are shown below: Age 24 30 22 25 33 27 36 58 37 47 54 a.

Absences 6 5 7 6 4 5 4 1 3 2 2

Prepare an XY scatter diagram of the results? Use Age on the X-axis and Absences on the Yaxis.

Absences

Absences by Age 8 7 6 5 4 3 2 1 0 0

10

20

30

40

50

60

70

Age

b.

Generalize your observations? Younger people are absent more often than older people.

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