Find the standard deviation of the frequency distribution:
x
f
x . f
Mean,
= 60 ÷ 20 =
3
1
2
2
2
4
8
3
7
21
4
6
24
5
1
5
Σ
20
60
x
f
x −
(x −
)
2
f(x −
)
2
1
2
1 − 3 = -2
4
2
x 4 = 8
2
4
2 − 3 = -1
1
4
x 1 = 4
3
7
3 − 3 = 0
0
7
x 0 = 0
4
6
4 − 3 = 1
1
6
x 1 = 6
5
1
5 − 3 = 2
4
1
x 4 = 4
Σ
20
22
Close Window
= 60 ÷ 20 = 3