Definition 35.2 High School Mathematics · Chapter 35 — Continuous Random Variables For XXX with density fff on III: E(X)=∫It f(t) dt,V(X)=∫I(t−E(X))2f(t) dt=E(X2)−E(X)2.\E(X) = \int_I t\,f(t)\,\dd t, \qquad \V(X) = \int_I \bigl(t - \E(X)\bigr)^2 f(t)\,\dd t = \E(X^2) - \E(X)^2 .E(X)=∫Itf(t)dt,V(X)=∫I(t−E(X))2f(t)dt=E(X2)−E(X)2. Read in context →