In mathematics and statistics, the arithmetic mean is the sum of a collection of numbers divided by the count of numbers in the collection.
Simple arithmetic mean (or mean or average)
$$\bar{a}=\frac{a_{1}+a_{2}+...+a_{n}}{n}=\frac{1}{n} \times \sum_{i=1}^{n}a_{i}$$
where,
a1, ...— data set;
n— number of values.
Weighted arithmetic mean
$$\bar{a}=\frac{a_{1}\times b_{1}+...+a_{n} \times b_{n}}{b_{1}+...+b_{n}}=\frac{\sum_{i=1}^{n}a_{i} \times b_{i}}{\sum_{i=1}^{n}b_{i}} $$
where,
b1, ...— non-negative weights.
See also:
Arithmetic Mean FAQ
What is arithmetic mean?
It is the sum of the values divided by the number of values.
What is weighted arithmetic mean?
It is the weighted sum of values divided by the sum of the weights.
