Random variable and probability distribution (Xmapsoutcomestorealnumbers;P(X=xᵢ)=pᵢ,Σpᵢ=1;ExpectedvalueE(X)=Σxᵢpᵢ)
jee-mainjee-advanced
X maps outcomes to real numbers; P(X=xᵢ)=pᵢ, Σpᵢ=1; Expected value E(X)=Σxᵢpᵢ
What each symbol means
| Symbol | What it stands for |
|---|---|
| X | Random variable |
| E(X) | Expected value (mean) |
| pᵢ | Probability of X=xᵢ |
When to use this
0 ≤ pᵢ ≤ 1 and Σpᵢ = 1. Var(X) = E(X²) − [E(X)]².