What this calculator does
Expected value of a discrete distribution works out mean and standard deviation of a discrete random variable from its outcomes and probabilities. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaE(X) = Σxᵢpᵢ; Var(X) = Σxᵢ²pᵢ − E(X)²
The inputs explained
| Field | What to enter |
|---|---|
| Outcomes (comma separated) | A list of numbers, separated by commas or spaces. |
| Probabilities (comma separated) | A list of numbers, separated by commas or spaces. |