1. Measures of Central Tendency Mean, Median, Mode, and Range

2. Mean The mean is the average number in a set of data. You will add up all the numbers and divide by the total numbers. Example: You have homework grades as follows:80, 80, 100, 100, 65, 75, 100 The sum of those grades is 600. There were 7 homework grades, so you will do the following: 600 ÷ 7 = 85.7 The average homework grade is 85.7

3. Median The median is the middle number in a set of data that is ordered from least to greatest. Example: The same 7 homework grades would need to be ordered from least to greatest first. 65, 75, 80, 80, 100, 100, 100 Now, you find the middle number by counting in from the ends. You see that 80 is in the middle. The median of this set of data is 80. If there are an even number of data, take the average of the two numbers in the middle.

4. Mode The mode is the number that occurs most often in a set of data. There may be more than one mode. The mode has to be a number that occurs more than one time. Example: In the homework example, the grade of 100 occurs three times, which is more than any other homework grade. The number 100 is the mode of this set of data.

5. Range The range is the difference between the largest number and smallest number in the set of data. The larger the range, the more variation there is in the data. The smaller the range, the less variation there is in the data. Example: In the homework example, the highest grade was 100 and the lowest was 65. The difference is 35, so 35 is the range.