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Standard Deviation
Σfx2 – x2
n
Σfx2 – Σfx 2
n n( )
OR
( )
( )
Value Frequency F * x FX * x
x F FX FXX
1 1
2 3
3 5
4 4
5 3
6 2
7 2 Σ
1
12
14
6
15
16
15
98
72
75
64
45
12
1
20 79 367
Standard Deviation
Σfx2 – Σfx 2
Σf Σf( )( )
( - )36720
79 2
20( )
x F FX FXXΣ 20 79 367
Standard Deviation
Σfx2 – Σfx 2
n n( )( )
( - )36720
79 2
20( )(18.35 – 3.952)
Standard Deviation
Σfx2 – Σfx 2
n n( )( )
( - )36720
79 2
20( )(18.35 – 3.952) =(18.35- 15.6025)
Standard Deviation
Σfx2 – Σfx 2
n n( )( )
( - )36720
79 2
20( )(18.35 – 3.952) =(18.35- 15.6025)( 2.7475) = 1.66