The following stem-and-leaf plot represents a sample of exam
scores.
Exam Scores
4 | 5 6 8
5 | 3 4 5 6 9
6 | 2 3 5 6 6 9 9
7 | 0 1 1 3 3 4 5 5 5 7 8
8 | 1 2 3 6 9
9 | 3 5 7 8
The variance & coefficient of variation for the examination
scores is
QQQQ
From the stem and leaf plot
## by using Excel:
x x^2
45 2025
46 2116
48 2304
53 2809
54 2916
55 3025
56 3136
59 3481
62 3844
63 3969
65 4225
66 4356
66 4356
69 4761
69 4761
70 4900
71 5041
71 5041
73 5329
73 5329
74 5476
75 5625
75 5625
75 5625
77 5929
78 6084
81 6561
82 6724
83 6889
86 7396
89 7921
93 8649
95 9025
97 9409
98 9604
tot 2492 184266
The sample mean is given by
The variance of X is
The variance is
The standard deviation is
The coefficient of variation is given by
Hence coefficient of variation is
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