How to Create a Binomial Distribution Graph in Excel


The binomial distribution is used to describe the probability of obtaining k successes in n binomial experiments.

A binomial experiment is an experiment that has the following properties:

  • The experiment consists of n repeated trials.
  • Each trial has only two possible outcomes.
  • The probability of success, denoted p, is the same for each trial.
  • Each trial is independent.

If a random variable X follows a binomial distribution, then the probability that X = k successes can be found by the following formula:

P(X=k) = nCk * pk * (1-p)n-k

where:

  • n: number of trials
  • k: number of successes
  • p: probability of success on a given trial
  • nCk: the number of ways to obtain k successes in n trials

The following example explains how to create a binomial distribution graph in Excel.

Example: Binomial Distribution Graph in Excel

To create a binomial distribution graph, we need to first decide on a value for n (number of trials) and p (probability of success in a given trial):

Next, we need to create a column for each possible number of successes:

Next, we can use the BINOM.DIST() function to calculate the binomial probability for the first number of successes:

We can then copy and paste this formula to the remaining cells in column B:

Lastly, we can highlight each of the binomial probabilities, then click the Insert tab along the top ribbon, then click the Insert Column or Bar Chart icon in the Charts group:

The x-axis of the graph shows the number of successes in 8 trials and the y-axis shows the corresponding probability of that many successes.

Note that if you change the value for either n or p, the graph will automatically change to reflect the new probabilities.

Additional Resources

An Introduction to the Binomial Distribution
Understanding the Shape of a Binomial Distribution
5 Real-Life Examples of the Binomial Distribution

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