QUESTION 1: If all sample averages on an X- - chart fall within the control limits, all output will be conforming.
True
False
QUESTION 2: Process control and process capability are synonymous terms.
True
False
QUESTION 3: When monitoring attribute data using a p-chart, if the subgroup size is not constant, variable control limits can be established.
True
False
QUESTION 4:
If the mean contaminant count per squared millimeter is 5.8, then the center line for a c-chart that plots the contaminant count per squared centimeter is 580.
True
False
QUESTION 5: When constructing control limits, if special causes are found, they are eliminated and the control limits recomputed because the special cause points do not represent a state of statistical control.
True
False
QUESTION 6: The s-chart is used to monitor variation.
True
False
QUESTION 7: An s-chart utilizes the range instead of the standard deviation utilized in R-charts.
True
False
QUESTION 8: Control charts for individual variables data require calculation of a moving range.
True
False
QUESTION 9: Subgroup samples should be chosen so that, if assignable causes are present, the chance of observing differences between samples is low, while the chance of observing differences within a sample is high.
True
False
QUESTION 10: For variables data, sample size can be calculated by specifying the desired minimum shift in the process mean to be detected.
True
False
QUESTION 11: A process is deemed "out of control" when
common causes are present.
special causes are present.
data varies around the mean.
defective rate is high.
QUESTION 12: ________ developed the first control charts.
G. Taguchi
Walter Shewhart
W. Edwards Deming
Dr. Joseph Moses Juran
QUESTION 13: A manufacturing company producing circuit boards will randomly sample 60 circuit boards per day and record the number of defects contained in each of these boards. Management wants to plot the number of defects in all the circuit boards sampled. What control chart is most appropriate?
X- -chart
p-chart
np-chart
c-chart
QUESTION 14: A delivery company defines a "defective" as a package delivered later than the promised delivery time. Management wants to monitor the proportion of packages delivered per week beyond the promised delivery time. Management is willing to sample 150 packages per week and determine which of these packages are "defective." What control chart is most appropriate?
X- -chart
R-chart
p-chart
c-chart
QUESTION 15: Determine the sample standard deviation for the following sample data: 7, 9, 2, 0, 1 and 5.
3.3466
3.2660
2.9933
3.5777
QUESTION 16: Suppose that a substrate is built from layers so that its thickness is the sum of the thicknesses of each layer. The thickness of each layer has the following means and standard deviations. What is the probability that the substrate thickness exceeds 110 units?
Layer, Mean, Standard deviation
1, 20, 4
2, 30, 8
3, 50, 10
0.325
0.227
0.478
0.536
QUESTION 17: In the application of an xbar control chart with the usual 3-sigma limits, if the subgroup sample size is increased
the Type I errors decrease, and the Type II errors increase.
the Type I errors remain the same and the Type II errors increase.
the Type I errors remain the same and the Type II errors decrease.
both the Type I and Type II errors decrease.
QUESTION 18: For an xbar and R control chart use the following summary statistics: X= = 10.0, r- =2.3, and n = 4 to answer the following questions. (Note: Use the above scenario and data to answer questions 18-20.)
Calculate an unbiased estimate of σ.
2.4965
1.117
2.039
2.883
QUESTION 19: (Use scenario from question 18 above.)
Calculate the upper control limit for an xbar control chart.
16.9
13.35
14.234
11.677
QUESTION 20: (Use scenario from question 18 above.)
Calculate the upper control limit for an R control chart.
5.249
9.146
14.234
9.26
QUESTION 21: For an xbar and s control charts given the following summary statistics: X= = 10.0, S- =2.3, and n = 4. Calculate an unbiased estimate of σ.
2.039
1.117
2.497
2.883
QUESTION 22: Assume σ gage = 2.497. The upper specification limit USL=16 and lower specification limit LSL = 4. Using k=6, what is the precision-to-tolerance (P/T) ratio?
1.0195
0.565
1.2465
1.4415
QUESTION 23: Twenty-five samples, of size 30 were collected and a total of 48 nonconforming items were found. The three sigma upper control limit for a p-chart is
0.198
0.091
0.211
0.833
QUESTION 24: Given that σ process = 4.7 and σ gage = 3.4. What is the total standard deviation in data from this process?
3.245
8.1
5.801
33.65
QUESTION 25: Given an 3-sigma xbar chart for n = 4 with UCL = 16 and LCL = 4, the estimated process standard deviation is
4
2
16
8
QUESTION 26: SPC is a tool for determining when and if special causes are present in a process.
True
False
QUESTION 27: If all the points on a control chart are within the control limits, then the process yield is excellent.
True
False
QUESTION 28: Control limits for variables and attribute data utilize the same mathematical formulas.
True
False
QUESTION 29: A p-chart is a control chart used with binomial attribute data.
True
False
QUESTION 30: Control charts for c-chart are based on the normal distribution.
True
False
QUESTION 31: Variation in process output can occur as a result of chance or as a result of assignable causes.
True
False
QUESTION 32: A Type I error occurs when an incorrect conclusion is reached that a special cause is present when in fact one does not exist.
True
False
QUESTION 33: Control limits are the same as specification limits.
True
False
QUESTION 34: The normality assumption is more critical for X- charts than for x-charts.
True
False
QUESTION 35: An EWMA chart can be used to detect a smaller shift in the process mean than can be easily detected with an x- chart.
True
False
QUESTION 36: If a process is neither capable nor in control, the desired first step is to
remove sources of common causes of variation.
redesign the equipment.
remove sources of special causes of variation.
determine the process capability index.
QUESTION 37: A semiconductor company takes thickness measurements at 5 sites on a wafer. To monitor the uniformity of the thickness what control chart is most appropriate?
X- -chart
c-chart
p-chart
s-chart
QUESTION 38: For variables data, the sample means are assumed to be
densely distributed.
normally distributed.
Poisson distributed.
correlated.
QUESTION 39: To form rational-subgroups for an X- -chart, the goal is to have the samples be as ______ as possible.
heterogeneous
homogeneous
large
equally spaced
QU'TION 40: The output of a process is stable and normally distributed. If the process mean equals 23.5, what percent of output will be smaller than the mean?
10%
30%
50%
Cannot be determined without the standard deviation
QUESTION 41: Assume that the mean number of surface flaws per square meter is 2.8. An inspection operation checks two square meters of panels on each of three panels in a lot. The total number of flaws is plotted on a control chart. What is the upper control limit for a c-chart with 3-sigma control limits?
5.020
7.099
12.296
29.096
QUESTION 42: If the traditional three-sigma limits on a control chart are replaced by two-sigma limits, which of the following is true?
The Type I error decreases
The Type II error remains the same
The center line decreases
The Type I error increases
QUESTION 43: Because of high test costs, a single sample of wastewater sludge is tested daily for dissolved oxygen content. The appropriate control chart method is
X- -chart and R-chart.
c-chart.
x-chart and the moving range chart.
x-chart and R-chart.
QUESTION 44: Calculate an EWMA control chart for a process with mean = 20 and standard deviation = 2. The subgroup size is n = 4. Use λ = 0.2 and 3-sigma control limits. What are the control limits for the second plotted point (at sample 2)?
21.537
21.241
20.768
19.645
QUESTION 45: A precision parts manufacturer produces bolts for use in military aircraft. Ideally the bolts should be 37.50 centimeters (cm) in length. The specifications for length are 37.50 ± 0.25 cm. The company has established an X- -chart and an R-chart using samples of size five. The centerline for the X- -chart is equal to 37.65 cm and the centerline for the R-chart is equal to 1.03 cm. (Note: Use the above scenario and data to answer questions 20-22.)
What is the value of Cp for this process?
0.188
1.333
0.301
0.166
QUESTION 46: (Use the scenario in question 20 above.)
What is the value of Cpk for this process?
0.09
0.28
0.075
0.03
QUESTION 47: (Use the scenario in question 20 above.)
Calculate the upper control limit for the control chart with the usual 3-sigma limits.
38.24431
39.5864
39.11981
41.01501
QUESTION 48: Given the following data calculate C+ for the 6th sample for a CUSUM control chart for the subgroup means with K = 1. n = 4: and target value μ = 20.
Sample 1, 2, 3, 4, 5, 6, 7
Subgroup Mean 22, 15, 20, 19, 23, 23, 24
0
2
3
4
QUESTION 49: A CUSUM control chart is applied to a process with mean = 20 mm and standard deviation = 0.2mm. The subgroup size is n = 4. If the guideline that H is set to 5 standard deviations is used, what is the ARL of the chart for a mean shift to 20.1 mm?
38.0
10.4
5.75
4.01
Question 50: Given a 3-sigma xbar chart with n = 4 and centerline CL = 10 and control limits UCL = 16, LCL = 4. The ARL if the mean shifts from 10 to 12 is
5.51
24.45
43.86
52.46