"Average"
It is the process in which there are number of different quantities of same kind, and we determine a single quantity which when altered to each quantity will give the same total as the quantities do. It means that if a man has eaten 3 sweets on Monday, 5 sweets on Tuesday , 4 sweets on Wednesday. He has eaten 12 sweets in all. If we want to distribute these 12 sweets equally each day he has eaten 4 sweets.
There are three types of averages:
1. Arithmetic mean.
2. Median.
3. Mode.

Arithmetic Mean:
The above mentioned average is also called Mean. Average is simply the process in which we add the total number of quantities and divide them by the total number of quantities.
Example:

1) Find the average of the following numbers:
90, 87, 65, 56, 77, 69
Average = Sum of quantities / Number of quantities.
Sum = 90 + 87 + 65 +
Sum = 90 + 87 + 65 + 56 + 77 + 69 = 444
Number = 6
Average = 444 / 6 = 74

2) Jack scored 42, 65, 12, 33, 53, 42, 11, 2, 23 runs in 8 matches. What is his average score?
Total number of score = 42 + 65 + 12 + 33 + 53 + 42 + 11 + 2 + 23 = 283
Total number of matches = 8
Average score = 283 / 8 = 35.375

3) The average of 3 daughters is 19 years. If the age of mother is included then the average becomes 23. Find the age of mother?
Total age of the daughters = 19 x 3 = 57
Total age when the age of mother is included = 23 x 4 = 92
Mother's age = 92 - 57 = 35 years.

Median:
The median is the middle value of a set of data when they are arranged in increasing or decreasing order. If the set has an odd number of data(values), the middle number in this ordering is the median. If the set has even number of data(values), the median is the sum of the two middle numbers, divided by 2.
The number of values greater or equal to the median is equal to the number of values less than or equal to the median.
Example:

1. The students in Sara's class have the following ages: 4, 9, 5, 3, 4, 11, 12, 7, 13, 3. Find the median of their ages?
The data (values) arranged in increasing order are:
3, 3, 4, 4, 5, 7, 9, 11, 12, 13. The number of ages is even. And the middle numbers are 5 and 7 , which are the 5th and 6th. The median is the average of these two numbers:
(5 + 7 ) / 2 = 12 / 2 = 6.

2. The haviest 7 persons in an office have weights in kgs 41, 60, 47, 42, 44, 42, and 47. Find the median of their weights?
The arranged in increasing order is 41, 42, 42, 44, 47, 47, 60. The values are odd in number and the middle number is the 4th number. We see that the median is 44.

Mode:
It is the most frequent number in a list of number.
Example:
2, 4, 6, 7, 4, 8, 4, 2, 4, 5, 4
The mode for the given list or data is "4".

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