# Averages Concept for CAT Examination

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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.
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