2.5 RANDOMVARIABLES AND PROBABILITY DISTRIBUTION FUNCTION (PDF) he probability distribution function or probability density function (PDF)of a random variable X: the values taken by that random variable and their associated probabilities 1. PDF of a discrete random variable Discrete rv. (x takes only a finite (or countably infinite) number of values various values of the random variable /o d Probability distribution or probability density function (PDf)-it shows how the probabilities are spread over or distributed over the PDF of a discrete r.v.X f(X)=P(X=X) for i=1, 2, 3., n And 0 forX≠X2.5 RANDOM VARIABLES AND PROBABILITY DISTRIBUTION FUNCTION (PDF) • The probability distribution function or probability density function (PDF) of a random variable X: the values taken by that random variable and their associated probabilities. • 1.PDF of a Discrete Random Variable Discrete r.v.（X） takes only a finite（or countably infinite） number of values. • Probability distribution or probability density function (PDF)—it shows how the probabilities are spread over or distributed over the various values of the random variable X. • PDF of a discrete r.v.(X) f(X)= P(X=Xi ) for i=1,2,3...,n And 0 for X≠Xi