By Katie Proctor
Updated Aug 30, 2022
The term expected value describes the long‑term average outcome of an experiment performed repeatedly. In practice, it is simply the arithmetic mean of a set of numbers. Whether you’re measuring the average yearly snowfall in your city or the typical age of homes in your neighborhood, finding the expected value is straightforward once you follow a few clear steps.
Identify the quantity of elements you will include in your calculation. For example, to determine the expected weight of students in a class, first count the number of students. We’ll denote this number as n. If there are 20 students, then n = 20.
Write down the value of every item. Continuing the classroom example, list the weight of each of the 20 students. You should have exactly 20 figures, one for each individual.
Add all recorded values together to obtain a single total. Double‑check the addition to ensure accuracy. For instance, if the combined weight of all students is 2,143 lb, that is the sum you’ll use.
Divide the total from Step 3 by the number of items from Step 1. Using the example, 2,143 lb ÷ 20 students yields an expected mean weight of 107.15 lb.
