STATISTICS - MEAN AND STANDARD DEVIATION

 MEAN AND STANDARD DEVIATION



  x ᵢ

fᵢ

fᵢxᵢ

xᵢ²

fᵢxᵢ²

3

1

3

9

9

4

1

4

16

16

5

2

10

25

50

6

3

18

36

108

7

6

42

49

294

8

3

24

64

192

9

2

18

81

162

10

1

10

100

100

11

1

11

121

121

Total

20

140


1052


Mean = Σfᵢxᵢ / Σfᵢ = 140 / 20 = 7



Standard deviation


𝞂 = (1/N)√[NΣfᵢxᵢ²  - (Σfᵢxᵢ)²]


   = (1/20) √[20(1052) - (140)²]


   = (0.05) √(21040 - 19600)


   = (0.05) √1440


   = (0.05)(37.947)

= 1.897

= 1.9




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