What is Average
An average or more accurately an arithmetic mean is, in crude terms, the sum of n different data divided by n.
Averages of a group is defined as the ratio of sum of all the items in the group to the number of items in the group.
Average = (Sum of all items in the group)/ Number of items in the group
Now, sum of all items can be ‘the sum of number of quantities like apple, people etc’ or ‘sum of values of the item like 10 coins of 2Rs each etc’.
Some Important Concepts:
1. Average =total of data/No.of data
2. If the value of each item is increase by the same value a, then the average of the group or items will also increase by a.
3. If the value of each item is decreased by the same value a, then the average of the group of items will also decrease by a.
4. If the value of each item is multiplied by the same value a, then the average of the group or items will also get multiplied by a.
5. If the value of each item is multiplied by the same value a, then the average of the group or items will also get divided by a.
6. If we know only the average of the two groups individually, we cannot find out the average of the combined group of items.
7.Average of n natural no's=(n+1)/2
8.Average of even No'=(n+1)
9.Average of odd No'= n
10.General Formula=(1st number +Last number)/2
