Deck 4: Statistical Process Control

Question 1

For a process control chart a process is generally considered to be in control if

A)most points are near the center line
B)approximately an equal number of sample points are above and below the center line
C)there is no discernible pattern to the sample points
D)all of the above

Answer 1

D

Question 2

In a process where a large number of defects are likely to occur

A)C_p < 1.0
B)C_p = 1.0
C)C_p > 1.0
D)C_p = C_pk

Answer 2

A

Question 3

In order to determine if the time required for students to take a final exam is excessive,five students were selected at random from each of six classes.If the process average is 123.77 minutes and the average range is 66.83 minutes,the upper and lower control limits of a 3-sigma x-chart are

A)UCL = 187.35,LCL = 109.95
B)UCL = 157.80,LCL = 89.80
C)UCL = 176.66,LCL = 120.33
D)UCL = 162,53,LCL = 89.01

Answer 3

D

Question 4

An example of a product or service quality attribute is

A)the weight of a bag of potato chips
B)the time it takes to serve a customer at a store
C)the completeness of an online retail order
D)the temperature of a cup of coffee at a barista

Question 5

If samples of 100 for a process are taken and p is 0.15,the upper and lower control limits for a 3-sigma p-chart are

A)UCL = 0.190 ,LCL = 0.010
B)UCL = 0.257,LCL = 0.043
C)UCL = 0.322,LCL = 0.000
D)UCL = 0.045,LCL = 0.005

Question 6

In order to determine if the time required for students to take a final exam is excessive,five students were selected at random from each of six classes.If the process average is 123.77 minutes and the average range is 66.83 minutes,the upper and lower control limits of a 3-sigma R-chart are

A)UCL = 141,LCL = 0
B)UCL = 133.6,LCL = 0
C)UCL = 96,LCL = 0
D)UCL = 152.3,LCL = 0

Question 7

In a "zone" pattern test each zone is how many standard deviations wide?

A)1
B)1/3
C)2
D)A₂R

Question 8

In an Excel spreadsheet for a p-chart,if the total number of defectives for 20 samples of 100 observations each is in cell F26,the Excel formula for p is

A)=F26)/20)*100))
B)=F26)/20)
C)=F26)*100))/20
D)=F26)*20))/100

Question 9

One of the general guidelines for identifying a pattern in a control chart is

A)14 points on one side of the center line
B)4 out of 5 consecutive points in zone A on one side of the center line
C)8 consecutive points on one side of the center line
D)8 consecutive points alternating up or down

Question 10

Wider control limits on a process control chart i.e. ,3 sigma as opposed to 2 sigma limits)makes the chart

A)more sensitive to changes in the process
B)correspond to an overall normal probability of 95%
C)have a higher probability that the sample values will fall outside the control limits
D)harder to show changes in the process that are not random

Question 11

If the process capability index,C_pk.is greater than 1.00_,then

A)the process is not capable of meeting design specifications
B)the process is capable of meeting design specification
C)the process corresponds to six sigma quality
D)the process will generate defects

Question 12

Statistical process control is a tool primarily for

A)identifying process variability due to natural occurrences
B)accepting or rejecting products
C)identifying process variability due to nonrandom causes
D)training workers for a production process

Question 13

A cookie company makes chocolate chip cookies and it wants them to average 8 chocolate chips apiece.To control the quality of the production process the company should use a

A)p-chart
B)x-chart
C)x-chart and r-chart together
D)c-chart

Question 14

Control charts are typically used

A)at every step in a production or service process
B)at the beginning and end of a production or service process
C)at critical points where it is particularly costly if the process goes out of control
D)at labor intensive points in the process

Question 15

If 20 samples of a production process are taken and there are 240 total defects,the upper and lower control limits for a 3-sigma c-chart are

A)UCL = 16.472,LCL = 7.528
B)UCL = 15.464,LCL = 8.536
C)UCL = 22.392,LCL = 1.608
D)UCL = 18.728,LCL = 5.272

Question 16

A p-chart and R-chart are control charts for

A)variables
B)attributes
C)attributes for a p-chart and variables for a R-chart
D)attributes for a R-chart and variables for a p-chart

Question 17

At a fast-food restaurant,if the average time to serve a customer is 3.75 minutes for 10 samples of size 5,and the average range for the samples is 0.50 minutes,the upper and lower control limits for a 3-sigma x-chart are

A)UCL = 4.04,LCL = 3.46
B)UCL = 5.08,LCL = 4.94
C)UCL = 5.75,LCL = 1.75
D)UCL = 3.91,LCL = 3.60

Question 18

In an Excel spreadsheet for a c-chart,if the population process average for 20 samples,c,is in cell H4,the Excel formula for the upper control limit is

A)=H4+3*SQRTH4*1-H4))/100))
B)=H4+3*SQRTH4/20)
C)=H4+3*SQRTH4)
D)=H4+SQRT3*H4)

Question 19

An attribute control chart that uses the actual number of defects per item in a sample is a

A)p-chart
B)mean chart
C)range chart
D)c-chart

Question 20

In general,sample sizes for attribute control charts are

A)smaller than for variable control charts
B)larger than for variable control charts
C)the same as for variable control charts
D)larger or smaller than variable control charts

Question 21

Product design specifications that are twice as large as the natural variations for 3-sigma control chart limits reflects

A)Pareto level quality
B)ISO 9000 certification
C)Baldrige Award criteria
D)Six Sigma

Question 22

The design specifications that reflect customer requirements for a product are

A)control limits
B)process capabilities
C)attributes
D)tolerances