Probability & Combinatorics
Intermediate

Expected Value

Long-run average value of a random variable.

Formula

E[X]=∑ixi piE[X] = \sum_{i} x_i\, p_i

Variables

x_iOutcome value
p_iProbability

Example

Die roll: E = 3.5

Did You Know?

Expected value need not be an achievable outcome.

probabilitystatistics