Functions of Continuous Random Variables

Expectation of function of discrete r.v. .

Theorem: If is a continuous random variable and is a function, then

Example. You throw a dart at a circular board of radius 1 ft. It hits a point on the board uniformly at random, and you win \frac{1}{r}r$ ft from the center. What are your expected winnings?

where X = distance of point to center, Missing close brace\mathbb{E}[W]=\int _{-\infty}^{\infty}g(t)f_{X}(t) \, dt=\int _{0}^{1} \frac{1}{t}2t \, dt=\int _{0}^{1}2 \, dt=\boxed{\2}$

Example. Suppose is a r.v. w/ cdf . Is discrete or continuous? If so, calculate (i) the mean of , (ii) , and (iii) .

continuous and piecewise continuously differentiable is a continuous r.v. (i) (ii) (iii)