A quality control analyst for a light bulb manufacturer is c

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.

Day

-

X (in minutes)

R

1

58.5

5.1

2

47.6

7.8

3

64.3

6.1

4

60.6

5.7

5

63.7

6.2

6

57.5

6

7

55

5.4

8

54.9

6.1

9

55

5.9

10

62.7

5

11

61.9

7.1

12

60

6.5

13

58.3

5.9

14

52

5.2

1) Suppose the analyst constructs an R chart to see if the variability in production times is in-control. What is the center line of this R chart?

a) 4.8

b)6.0

c)6.9

d)7.1

2) Suppose the analyst constructs an R chart to see if the variability in production times is in-control. What is the upper control limit of this R chart?

a) 10.66

b)9.37

c) 7.98

d) 6.34

3) Suppose the analyst constructs an R chart too see the variability in production times is in-control. The R chart is characterized by which of the following.

a) increasing trend

b) decreasing trend

c) in control

d) points outside the control limits

4) suppose the analyst constructs an x chart to see if the production process is in control. What is the center line for this chart?

a)64.3

b)59.5

c)58

d) 57.1

5) ) suppose the analyst constructs an x chart to see if the production process is in control. What is the lower control for this chart?

6) suppose the analyst constructs an x chart to see if the production process is in control. Which expression best describes this chart?

a) in control

b) increasing trend

c) decreasing trend

d) Individual outliers

Day	- X (in minutes)	R
1	58.5	5.1
2	47.6	7.8
3	64.3	6.1
4	60.6	5.7
5	63.7	6.2
6	57.5	6
7	55	5.4
8	54.9	6.1
9	55	5.9
10	62.7	5
11	61.9	7.1
12	60	6.5
13	58.3	5.9
14	52	5.2

Solution