This exercise set contains some solved exercises on discrete random variables and probability mass functions. The theory needed to solve these exercises is introduced in the lecture entitled Random variables.
Let
be a discrete random variable. Let its support
be:
Let its probability mass function
be:
Calculate the following
probability:
Using the
additivity of
probability:![[eq5]](http://images1.statlect.com/random_variables_exercise_set_1__7.png)
Let
be a discrete random variable. Let its support
be the set of the first
natural
numbers:
Let its probability mass function
be:
Compute the
probability:
By the
additivity of
probability:![[eq10]](http://images1.statlect.com/random_variables_exercise_set_1__15.png)
Let
be a discrete random variable. Let its support
be:
Let its probability mass function
be:
where
is the binomial coefficient.
Calculate the
probability:
First note that, by
additivity:
Therefore, in order to compute
,
we need to evaluate the probability mass function at the three points
,
and
:
Finally:![[eq19]](http://images1.statlect.com/random_variables_exercise_set_1__29.png)