Binomial Distribution

Earlier, we found the theoretical probability for our game and compared it with the experimental one. Finding the probability without conducting an experiment means that we can find the probability using just pen and paper and with minimal effort.

Now, let’s try to generalise it — let’s say that the probability of getting 1 red ball in one trial is equal to p. In that case, what would be the probability of all 4 balls being red? Let’s see in the following video.

So, the probability distribution for X (i.e., the number of red balls drawn after 4 trials) if the probability of getting a red ball in 1 trial is ‘p’ is as follows.

In the following video, we will see how this can be generalised even further.

So, the formula for finding binomial probability is given by:

P(X=r)= nCr(p)r(1−p)n−r

Where n is the number of trialsp is the probability of success, and r is the number of successes after n trials.

However, there are some conditions that need to be met in order for us to be able to apply the formula.

  • The total number of trials is fixed at n.
  • Each trial is binary, i.e., it has only two possible outcomes: success or failure.
  • Probability of success is the same in all trials, denoted by p.

Report an error