In calculation of arithmetic mean, the importance of all the items was considered to be equal. However, there may be situations in which all the items under considerations are not equal importance. For example, we want to find average number of marks per subject who appeared in different subjects like Mathematics, Statistics, Physics and Biology. These subjects do not have equal importance. If we find arithmetic mean by giving Mean.
Weighted Arithmetic Mean is computed by using following formula:
Stands for weighted arithmetic mean.
Stands for values of the items and
Stands for weight of the item
Now we will find weighted arithmetic mean as: