The mean (average) of a data set is found by adding all numbers in the data set and then dividing by the number of values in the set. The median is the middle value when a data set is ordered from least to greatest. The mode is the number that occurs most often in a data set.

The empirical relationship between mean, median and mode is: Mean=Median=Mode. C. Mode−Mean=3(Median−Mean)

If a frequency distribution graph has a symmetrical frequency curve, then mean, median and mode will be equal. Mean = Median = Mode. For Positively Skewed Frequency Distribution.

A quartile divides data into three points—a lower quartile, median, and upper quartile—to form four groups of the dataset. The lower quartile, or first quartile, is denoted as Q1 and is the middle number that falls between the smallest value of the dataset and the median. The second quartile, Q2, is also the median.

Example: The median of 4, 1, and 7 is 4 because when the numbers are put in order (1 , 4, 7) , the number 4 is in the middle. Mode: The most frequent number—that is, the number that occurs the highest number of times.

How to find the mean, median and mode: MEAN

1. Step 2: Add the numbers up to get a total. Example: 2 +19 + 44 + 44 +44 + 51 + 56 + 78 + 86 + 99 + 99 = 622.
2. Step 3: Count the amount of numbers in the series.
3. Step 4: Divide the number you found in step 2 by the number you found in step 3.

Median

1. Arrange your numbers in numerical order.
2. Count how many numbers you have.
3. If you have an odd number, divide by 2 and round up to get the position of the median number.
4. If you have an even number, divide by 2. Go to the number in that position and average it with the number in the next higher position to get the median.

The median formula is {(n + 1) ÷ 2}th, where “n” is the number of items in the set and “th” just means the (n)th number. To find the median, first order the numbers from smallest to largest. Then find the middle number.