ods333 chapter 17

TRUE or FALSE

28. T F It
is impossible to develop a process that has zero variability.

29. T F
Assignable variations in a process are also called natural variations.

30. T F An
x-bar chart would be appropriate to monitor the number of defects in
a
production lot.

31. T F The
central limit theorem provides the statistical foundation for control

charts.

32. T F If
we are tracking quality of performance for a class of students, we should
plot
the pass/fail result on a p-chart.

33. T F
Sample sizes of five (5) are often used when building control charts.

34. T F If
we are attempting to control the diameter of bowling balls, we will find
a
p-chart to be quite helpful.

35. T F A
c-chart would be appropriate to monitor the number of weld defects on
the
steel plates of a ship’s hull.

MULTIPLE CHOICE

36. Bags of pretzels
are sampled to ensure proper weight. The overall average for the
samples is nine
(9) ounces. Each sample contains 25 bags. The standard deviation
is estimated to
be three (3) ounces. The upper control chart limit ( for 99.7% confi-
dence ) for the
average would be____ounces.

a. 9.4
b. 18.0
c.
10.2
d. 7.2
e. 10.8

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37. R-charts measure
changes in:

a. central tendency.
b. degree of variation.
c. number of defects per production lot.
d. natural variations.
e. none of the above.

38. Bags of chocolate
candy are sampled to ensure proper weight. The overall average
for the samples
is 36 ounces. Each sample contains twelve bags. The average range
is 1.3 ounces.
The upper control chart limit for the average would be:

a. 36.3458
b. 35.6542
c. 38.3101
d. 36.6279
e. 37.1258

39. Bags of tea are
sampled to ensure proper weight. The overall average for the samples
is 8 ounces. Each sample contains 10 bags. The
average range is 0.1 ounces. What is
the lower limit
of the average chart?

a. 7.9692
b. 8.0308
c. 7.9076
d. 8.0924
e. 8.1024

40. The average range
of a process for packaging cereal is 1.1 ounces. If the sample size
is ten (10) , find the upper control chart
limit for the range chart.

a. 0.245
b. 1.955
c. 1.777
d. 0.223
e. 0.143

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41. Given the problem
statement in question 40, find the lower control chart limit for the
range chart.

a. 0.245
b. 1.955
c. 1.777
d. 0.223
e. 0.143

42. Defects in
computer hard-drives will usually render the entire computer worthless.
For a
particular model, the percent defective in the past has been 1%. If a sample
size of 400 is
taken, what would the 95.5% lower control chart limit be?

a. 0.00995
b. 0.00005
c. 0.00000
d. 0.01000
e. 0.09550

43. Defects in marble
countertops usually require the whole top to be reconstructed.
In one kitchen
shop, the percent defective in the past has been one (1) percent.
If a sample
size of 30 is taken, what should be the 95.5% percent upper control
limit?

a. 0.030
b.
0.000
c. 0.046
d. 0.064
e. 0.074

44. A firm has been
receiving complaints about the attitude of some sales clerks. Over a
10-day period,
the total number of complaints was 360.
The firm wishes to develop
a control chart
for the number of complaints. What would the upper control limit on
the number of
complaints per day be for a 3 sigma ( 99.7% ) control chart?

a. 18
b. 36
c. 42
d. 54
e. 62

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45. Given the same
problem statement above, the total number of complaints is now 250.
What would the lower control limit on the number of
complaints per day be for a
3 sigma (
99.7% ) control chart?

a. 20
b. 0
c. 15
d. 10
e. 202.6

46. Who introduced
control charts in 1924?

a. W. Edwards Deming.
b. Philip Crosby.
c. J.M. Juran.
d. William Shewhart.
e. Malcolm Baldrige.

47. To guarantee that
cans of soda are properly filled, some cans are sampled and the
amounts
measured. The overall average for the samples is 12 ounces. Each sample
contains 10
cans. The average range is 0.4 ounces. The lower control chart limit
for the average
would be:

a. 12.1232
b. 11.8768
c. 13.2000
d. 12.3080
e. 11.5500

48. The control
chart:

a. focuses on the time dimension of a system.
b. captures the natural variability in the
system.
c.
can be used for categorical, discrete, or continuous variables.
d. all of the above.

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

a. a control chart with a series of consecutive
points that are above the center line
and a
series of consecutive points that are below the center line.
b. a control chart in which no points fall
outside either the upper control limit or
the lower
control limit, and no patterns are present.
c. a control chart in which several points fall
outside the upper control limit.
e. all of the above.

50. A political
pollster randomly selects a sample of 100 voters each day for 8 successive
days and asks
how many will vote for the incumbent.
The pollster
wishes to construct a ‘p’ chart to see if the percentage favoring the in-
cumbent
candidate is too eratic.

Sample (Day) Number Favoring Incumbent

1 57

2 57

3 53

4 51

5 55

6 60

7 56
8 59

What is the
numerical value of the center line for the ‘p’ chart?

a. 0.53
b. 0.56
c. 0.63
d. 0.66

51. Given the problem
statement above, what is the numerical value of the lower control
limit for the
‘p’ chart?

a. 0.37
b. 0.41
c. 0.50
d. 0.71