Let x be the discrete random variable whose value is the number of successes in n trials.
The probability distribution function for x of the binomial distribution B(n,p) is defined as
Given that the random sample size is
let x represent number of customers who purchase running shoes
Let "p" be the probability of customers in a sporting goods store purchase a pair of running shoes.
It is given that 70% of the customers in a sporting goods store purchase a pair of running shoes.
Thus
Thus the Probability distribution of x is given by
, where