General Statistics
Worksheet
Basic Statistics 
Group Variance and Mean

Worksheet Tools - Weighted Mean and Group Variance - To compute the group mean and variance
from categorized data. Example

Steps: (1) Fill out table first with Class Midpoint, X and frequency, f.  (2) Use formulas to calculate group statistics
 
Class

Index, i

 Class
Midpoint
X
(1)		 Frequency
f

(2)
(4) =
(2) divided by (3)

(5)=
(1) x (4)

 X2

(6)=
(1) x (1)

(7)=
(2) x (6)
1            
2            
3            
4            
5            
6            
7            
8            
9            
10            
Sum, (3) 
n=		     Sum: 
Group mean

=

 Group Variance:

=
 
 

 Standard  deviation:                                                 
=