#### Mean, Median, Mode, & Range

**Mean**:

Mean is commonly known as the **average** of a given set of numbers. The mean is the sum of all the numbers in a given sequence divided by the length of the sequence.

Example: For the numbers 6, 4, 2, 7, 1 the mean or average is 4.

The sum of the numbers is 6 + 4 + 2 + 7 + 1 which is equal to 20.

And the length is 5 (i.e. we have 6, 4, 2, 7, and 1 : there are 5 numbers).

So, the mean is **20 ÷ 5** which is equal to 4.

**Median**:

When the length of the sequence is odd, the median is simply the **middle number** when the numbers are arranged from lowest to highest.

Example: the median of 6, 4, 2, 7, 1 is 4.

When the numbers are arranged from lowest to highest they are 1, 2, 4, 6, 7.

So, the median is 4 which is the middle number.

When the length of the sequence is even, the median is the mean of the two middle numbers when the numbers are arranged from lowest to highest.

Example-2: the median of 6, 4, 2, 7, 1, 5 is 4.5.

When the numbers are arranged from lowest to highest they are 1, 2, 4, 5, 6, 7.

So, the median is **(4 + 5) ÷ 2** which is 4.5.

**Mode**:

The mode is the **most frequently occurring** number in a given set of numbers.

Example: the mode of 6, 4, 2, 7, 2 is 2 as 2 is occuring most often.

**Range**:

The range of a set of numbers is the **difference between the lowest and the highest** values.

Example: the range of 6, 4, 2, 7, 2 is 5.

The lowest number is 2 and the highest number is 7 and so the difference is **7 - 2** which is **5**.