Average is mainly defined as the sum of observations divided by the number of observations. From the last 4-5 years, there have been at least 1-2 questions from the topic of the averages asked in CAT exam and we can expect this trend to continue.
Basic Formula for Average = Sum of all / number of quantities
Tricks for Fast Calculation –
When a person replaces another person then:
Age of the new person = Age of the person who left + / – (increase/decrease in average * total number of people)
When a person joins the group:
Age of new member= Previous average + / – (Increase/Decrease in average * Number of members including new member)
Here is a solved example for you to better understand the concept –
Weighted Average –
When we multiple groups whose individual averages are known then to find a combined average of all the elements we use the concept of weighted average. Here’s a solved example for you.