The mean or average of a set of numbers can be calculated by a simple formula.
- Step 1: Recognize the limits of mean or average values. The average or mean is a good representation of the center if the data has a symmetric distribution. In other cases the mean may not always be the best choice for describing the center.
- FACT: Students' mathematics scores on the SAT exam in the United States have shown an upward trend since 1990.
- Step 2: Consider negative numbers. To add a negative number to a positive number, simply subtract the negative number from the positive number and compute the average using the same procedure. For example, the average of 5 and -5 is 0 because, 5 plus negative 5 is equal to 0, and 0 divided by 2 equals 0.
- TIP: For larger groups of numbers be sure to use a calculator to ensure the most accurate answer.
- Step 3: Consider the case of two positive numbers. As an example, take the numbers 1 and 5. The average or mean is 3 because 1 plus 5 is 6, and 6 divided by 2 equals 3.
- Step 4: Think about larger groups of numbers. The average of 1, 5, 5, and 9 is 5, because 1 plus 5 plus 5 plus 9 equals 20, and 20 divided by 4 equals 5.
- Step 5: Understand that to calculate the mean or average of a group of numbers, you simply add up all the numbers, then divide by how many numbers there are.