Exam 19: Statistical Applications in Quality Management

SCENARIO 19-5 A manufacturer of computer disks took samples of 240 disks on 15 consecutive days.The number of disks with bad sectors was determined for each of these samples.The results are in the table that follows. -Referring to Scenario 19-5,a p control chart is to be made for these data.The estimate of the standard error of the proportion of disks with bad sectors is .

The principal focus of the control chart is the attempt to separate special or assignable causes of variation from common causes of variation.Which causes of variation can be reduced only by changing the system?

SCENARIO 19-1 A local newspaper has 10 delivery boys who each deliver the morning paper to 50 customers every day.The owner decides to record the number of papers delivered on time for a 10-day period for one of the delivery boys and construct a p chart to see whether the percentage is too erratic. -Referring to Scenario 19-1,what is the numerical value of the center line for the p chart?

Poke-Yoke devices establish ways to eliminate unnecessary housekeeping aspects of a work environment.

Which of the following situations suggests a process that appears to be operating in a state of statistical control?

Total Productive Maintenance focuses on methods that enable participants to reduce setup time for equipment and resources and materials needed for changeover.

SCENARIO 19-10 Below is the number of defective items from a production line over twenty consecutive morning shifts. -Referring to Scenario 19-10,based on the c chart,no opportunity appears to be present to render an improvement in the process.

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 is the value of the CPU index?

The control chart

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,what is the value of the CPU index?

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,an x̄ chart is to be used for the time required to register.One way to obtain the control limits is to take the grand mean and add and subtract the product of A₂ times the mean of the sample ranges.For this data set,the value of A₂ is .

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 R chart to see if the variability in production times is in-control.What is the upper control limit for this R chart?

Developing operational definitions for each critical-to-quality characteristic involves which part of the DMAIC process?

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 supervisor constructs an x̄ chart to see if the process is in-control.What are the lower and upper control limits of this chart?

The purpose of a control chart is to eliminate common cause variation.

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 upper 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,what is the value of d₂ factor?

The C_pk is a one-sided specification limit.

Variation due to the inherent variability in a system of operation is called

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 is the value of the C_p index?