A random variable is a numerical quantity whose value is determined by chance.

A discrete random variable is one that can assume only integer (whole number, 0, 1, 2, 3, 4, 5, 6, etc. ) Values.

A continuous random variable is one that can assume any value over a continuous range of possibilities.

The mean or expected value of a random variable is the sum of each values of the variable times its corresponding probability, p(x).

The Variance of a random variable is, 

Binomial Random Variable

The binomial distribution is the relative frequency of a discrete random variable which has only two possible outcomes.

A binomial experiment is an experiment with repeated trials yielding only two possible outcomes and is called a trial.

The binomial random variable x, is the number of successes in n trials, where x = 0, 1, 2, 3, ... ,n

The frequency distribution of x, the number of successes of a binomial variable,  is called a binomial distribution.

The cumulative probability distribution is a distribution where the values of the column are obtained by adding all the preceding entries for the values of P[x].

The standard deviation of a statistics (mean, p, etc.) is called the standard error