Exam 19: Statistical Applications in Quality Management

SCENARIO 19-9 The manufacturer of canned food constructed control charts and analyzed several quality characteristics.One characteristic of interest is the weight of the filled cans.The lower specification limit for weight is 2.95 pounds.The table below provides the range and mean of the weights of five cans tested every fifteen minutes during a day's production. -Referring to Scenario 19-9,an R chart is to be constructed for the weight.One way to create the upper control limit involves multiplying the mean of the sample ranges by D₄.For this data set,the value of D₄ is .

In the United States,the control limits on a control chart are placed so that they are 3 standard deviations above and below a central line.

SCENARIO 19-7 A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process.She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet.The results from 20 days of such evaluations are presented below. She also decides that the upper specification limit is 10 blemishes. -Referring to Scenario 19-7,an R chart is to be constructed for the number of blemishes.The center line of this R chart is located at .

SCENARIO 19-7 A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process.She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet.The results from 20 days of such evaluations are presented below. She also decides that the upper specification limit is 10 blemishes. -Referring to Scenario 19-7,an R chart is to be constructed for the number of blemishes.One way to create the lower control limit involves multiplying the mean of the sample ranges by D₃.For this data set,the value of D₃ is .

Quick Changeover Techniques establish ways to clean and maintain the necessary housekeeping aspects of a work environment.

SCENARIO 19-4 A factory supervisor is concerned that the time it takes workers to complete an important production task (measured in seconds)is too erratic and adversely affects expected profits.The supervisor proceeds by randomly sampling 5 individuals per hour for a period of 10 hours.The sample mean and range for each hour are listed below. She also decides that lower and upper specification limit for the critical-to-quality variable should be 10 and 30 seconds,respectively. -Referring to Scenario 19-4,suppose the sample mean and range data were based on 6 observations per hour instead of 5.How would this change affect the lower and upper control limits of an R chart?

A process is said to be out of control if

SS method focuses on preventing the causes of defects.

SCENARIO 19-7 A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process.She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet.The results from 20 days of such evaluations are presented below. She also decides that the upper specification limit is 10 blemishes. -Referring to Scenario 19-7,based on the R chart,it appears that the process is out of control.

SCENARIO 19-8 Recently,a university switched to a new type of computer-based registration.The registrar is concerned with the amount of time students are spending on the computer registering under the new system.She decides to randomly select 8 students on each of the 12 days of the registration and determine the time each spends on the computer registering.The range,mean,and standard deviation of the times required to register are in the table that follows. -Referring to Scenario 19-8,construct an x̄ chart for the time required to register.

SCENARIO 19-7 A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process.She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet.The results from 20 days of such evaluations are presented below. She also decides that the upper specification limit is 10 blemishes. -Referring to Scenario 19-7,an x̄ chart is to be used for the number of blemishes.The lower control limit for this data set is _____ ,while the upper control limit is _____ .

SCENARIO 19-4 A factory supervisor is concerned that the time it takes workers to complete an important production task (measured in seconds)is too erratic and adversely affects expected profits.The supervisor proceeds by randomly sampling 5 individuals per hour for a period of 10 hours.The sample mean and range for each hour are listed below. She also decides that lower and upper specification limit for the critical-to-quality variable should be 10 and 30 seconds,respectively. -Referring to Scenario 19-4,what percentage of the time it takes workers to complete an important production task will fall inside the specification limits?

SCENARIO 19-9 The manufacturer of canned food constructed control charts and analyzed several quality characteristics.One characteristic of interest is the weight of the filled cans.The lower specification limit for weight is 2.95 pounds.The table below provides the range and mean of the weights of five cans tested every fifteen minutes during a day's production. -Referring to Scenario 19-9,an R chart is to be constructed for the weight.The lower control limit for this data set is .

SCENARIO 19-7 A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process.She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet.The results from 20 days of such evaluations are presented below. She also decides that the upper specification limit is 10 blemishes. -Referring to Scenario 19-7,construct an x̄ chart for the number of blemishes.

SCENARIO 19-10 Below is the number of defective items from a production line over twenty consecutive morning shifts. -Referring to Scenario 19-10,the c chart suggests that the special cause of variation must be incorporated into the process to become part of the permanent ongoing process.

The cause of variation that can be reduced only by changing the system is _____ cause variation.

Maintaining the gains that have been made with a revised process in the long term by avoiding potential problems that can occur when a process is changed involves which part of the DMAIC process?

SCENARIO 19-6 The maker of a packaged candy wants to evaluate the quality of her production process.On each of 16 consecutive days,she samples 600 bags of candy and determines the number in each day's sample that she considers to be of poor quality.The data that she developed follow. -Referring to Scenario 19-6,a p control chart is to be constructed for these data.The center line for the chart should be located at .

SCENARIO 19-3 A quality control analyst for a light bulb manufacturer is concerned that the time it takes to produce a batch of light bulbs is too erratic.Accordingly,the analyst randomly surveys 10 production periods each day for 14 days and records the sample mean and range for each day. -Referring to Scenario 19-3,suppose the analyst constructs an x̄ chart to see if the production process is in-control.Which expression best describes this chart?

SCENARIO 19-10 Below is the number of defective items from a production line over twenty consecutive morning shifts. -Referring to Scenario 19-10,a c chart is to be constructed for the number of defective items.The center line of this c chart is located at .