Solution:Discrete random variables can take on either a finite or at most a countably infinite set of discrete values (for example, the integers).
Their probability distribution is given by a probability mass function which directly maps each value of the random variable to a probability. For example, the value of
X₁, takes on the probability P₁, the value of X₂, takes on the probability P₂, and so on. The probabilities P₁, must satisfy two requirements: every probability P₁ is a number between 0 and 1, and the sum of all the probabilities is 1. (P₁ + P₂ + ... + Pₖ = 1)
A discrete random variable has a countable number of possible values. Discrete random variable: obtained by counting values for which there are no in-between values, such as the integers 0, 1, 2, ...
Thus, The number of marks scored by students appearing in the examination is an example of discrete random variable.