The term expected value refers to the logic that over the long term of doing an experiment multiple times, you would " expect" this number. The expected value (mean) is simply the average of any set of numbers. Whether you are trying to find the average yearly snowfall for your city or the average age of homes in your neighborhood, you can quickly and easily find the expected value of any set of numbers with simple math.

Determine the number of items or variables that are to be calculated. For example, if you are trying to determine the expected value weight of students in your class, you must first count the number of students in your class. We'll call this number "n." If there are 20 students in the class, then n=20.

Determine the value of each item or variable. Using the classroom example, write down the weight of each student. You should have 20 weights written down because there are 20 students in the class.

## Sciencing Video Vault

Add all the values. Add together all of the weights into one large sum. Make sure you add each person's weight. Always figure the sum twice to make sure you have added correctly.

Dive by "n". Take the sum from Step 3 and divide by n from Step 1. For example, If the sum of all of the student's weights is 2,143, then divide 2,143 by 20. The expected value or average weigh of the students is 107.15.