A continuous random variable XXX has CDF F(x)=x2F(x) = \frac{x}{2}F(x)=2x for 0≤x≤20 \le x \le 20≤x≤2. What is the PDF?
f(x)=1/2f(x) = 1/2f(x)=1/2
f(x)=x/2f(x) = x/2f(x)=x/2
f(x)=xf(x) = xf(x)=x
f(x)=2xf(x) = 2xf(x)=2x