15.2.9 One dimensional random variables and their characteristics
Problem:
The density of the distribution of the random variable \( X \) has the form
\[
f(x)=\left\{\begin{array}{l}
0, \quad \text { when } x<0 \\
\frac{x^{m}}{m !} e^{-x}, \text { when } x>0
\end{array}\right.
\]
Find \( M X \) and \( D X \).