# Introduction to Random Variables

## Abstract

In this chapter, the basic concepts for both discrete and continuous random variables were introduced. The definition of a random variable, a discrete random variable, and a continuous random variable, and the formulae of the probability mass function, probability density function, cumulative distribution function, complementary cumulative distribution function (tail function), expected value of a random variable, expected value of a function of a random variable, and the variance and standard deviation of a random variable have been provided. In addition to the solutions of some typical examples and problems for the discrete and continuous random variables, one well-known problem, i.e. *newsboy* (*newsvendor*) *problem* has also been presented.