Average Calculator
* SD = standard deviation
Average calculation
The average (arithmetic mean) is equal to the sum of the n numbers divided by n:
Average =
sum
count
=
a1+a2+...+an
n
Example
The average of 1,2,5 is:
Average =
1+2+5
3
= 2.667
Weighted average calculator
Weighted average calculation
The weighted average (x) is equal to the sum of the product of the weight (wi) times the data number (xi) divided by the sum of the weights:
Example
Find the weighted average of class grades (with equal weight) 70,70,80,80,80,90:
Since the weight of all grades are equal, we can calculate these grades with simple average or we can cound how many times each grade apear and use weighted average.
2×70,3×80,1×90
x =
2×70+3×80+1×90
2+3+1
=
470
6
= 78.33333