Probability explained. Source: One Minute Economics 2017.

In mathematics, the notation \(\pi\), pronounced as \(pi\), denotes ratio of circumference of any circle to diameter of same circle. \(\pi\) is constant. It will not vary for circles of any size. But many other facts in the world are not constant.

Let's assume alphabet \(X\) denotes height of adults in India. \(X\) can take any positive real value for any random individual. Hence \(X\) is a variable that takes random values in a range of positive real numbers.

Probability measures how likely or unlikely is an outcome, where outcome is a Random Variable. For instance, we can ask, "What's the probability of picking an Indian adult male who is above six feet?"

Probability is intimately related to another branch of mathematics called Statistics. Both these are of fundamental importance to the field of Data Science.