1.) A product manager has conducted a customer satisfaction
survey of
30 customers on a scale of 1 to 5. The survey data is shown below. Calculate the mean and standard deviation of
the survey and plot a histogram of the data.
Does the distribution approximate Normal?
Customer
Satisfaction rating
1
4
2
3
3
2
4
5
5
5
6
2
7
1
8
4
9
3
10
4
11
4
12
5
13
3
14
3
15
2
16
1
17
5
18
3
19
4
20
3
21
4
22
2
23
4
24
4
25
3
26
3
27
3
28
2
29
2
30
3
2.) A customer relationship manager decided to track
customer complaints as part of his ongoing customer satisfaction improvement
program. After collecting data for two months, their check sheet appears as
follows:
Type of Problem
Frequency
(number of times)
Call went to voice mail
8
Items damaged when received
21
Literature not in the box
9
Parts missing
13
Unit not working
2
Delivery was late
3
Construct a Pareto chart including the cumulative %
frequency. What is the cumulative percentage of the two leftmost bars?
3.) A quality control engineer monitors the quality of a
cylinder production line. He regularly
selects a sample of 5 units and measures the diameters. The specification requires the diameter to be
6 inches plus/minus 0.1 inch. The
following is a record of the measurements.
Is the production process in control?
Please use X bar and R charts to make an assessment.
Sample
item 1
item 2
item 3
item 4
item 5
1
6.10
6.15
5.35
5.98
5.95
2
6.35
6.02
6.20
6.10
5.70
3
5.85
5.90
6.20
6.12
6.08
4
6.00
5.80
5.70
6.04
6.17
5
6.15
5.60
6.25
5.99
6.01
6
6.13
6.05
5.89
6.00
5.87
7
5.88
6.03
5.76
6.1 3
6.00
8
6.12
5.45
6.15
6.04
5.91
