HP 50g Graphing Calculator - Manual (Page 277)

Page 8-20
To calculate this last result, we can use the following:
The standard deviation of the grouped data is the square root of the variance:
N
s s w
w
s s w
V
n
k
k k
n
k
k
n
k
k k
∑
∑
∑
=
=
=
− ⋅
=
− ⋅
= 1
2
1
1
2 ) ( ) (