Let XXX have PDF f(x)=4π1−x2f(x) = \frac{4}{\pi}\sqrt{1-x^2}f(x)=π41−x2 for 0≤x≤10 \le x \le 10≤x≤1. What is E[X]E[X]E[X]?
13\frac{1}{3}31
12\frac{1}{2}21
π\piπ
43π\frac{4}{3\pi}3π4