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In Maths, Average is the central value of a list of numbers. In order to compute the Average of a list of numbers, we must take the sum of a list divided by the number of numbers in the list. Sometimes average is also referred to as the arithmetic mean.

Example:

To find the average of a given list of numbers { 2, 3, 7, 8, 10 }
Sum of the numbers = 2 + 3 +7 + 8 + 10 = 30
Count of the numbers = 5
Average = Sum/ Count = 30 / 5 = 6

Note: The average of a list of numbers may not always be a whole number, you may also get a decimal number as the result of the division.

Related terms:

Weighted average: The weighted average of a given list of numbers is similar to an ordinary average, except that instead of each of the numbers in the list contributing equally to the final average, some numbers contribute more ( or are weighted ) than others. If all weights are equal then the average and weighted average for the list of numbers will be the same. 

Median: Median is the middle value in the list of numbers. To find the median, you will first need to arrange your numbers in ascending order and then pick the middle number. Once you know the median, you can also find the lower and the upper quartiles of the list of numbers.

Practice questions:

Question: There are two divisions of class five in a school. Division A has 20 students and Division B has 30 students. The marks scored by the students of each class in a Geometry test are as given below:

Division A = 62, 67, 71, 74, 76, 77, 78, 79, 79, 80, 80, 81, 81, 82, 83, 84, 86, 89, 93, 98
Division B = 81, 82, 83, 84, 85, 86, 87, 87, 88, 88, 89, 89, 89, 90, 90, 90, 90, 91, 91, 91, 92, 92, 93, 93, 94, 95, 96, 97, 98, 99

What is the average and the weighted average of the marks scored by the students of class five?
( Answer:
    Average of marks scored in Division A = Sum/ count = 80
    Average of marks scored in Division B = Sum/ count = 90
    Average marks scored by Class five     = (Average of Div A + Average of Div B)/ 2
                        = ( 80 + 90 ) / 2 = 85
    Weighted average of marks scored by Class five = (( 20 * 80 ) + ( 30 * 90 )) / (20 + 30 )
=  4300 / 50
= 86    
)

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