A continuous random variable has the probability density function
$\displaystyle
f_x(x) \; = \; \begin{cases} \frac{1}{b-a} \qquad , \qquad a< x<b \\
0 \qquad, \qquad otherwise
\end{cases}
$
i) Find the cumulative distribution function and sketch it
ii) Find E[X] and Var X.