I am having a very difficult time trying to figure out when

I am having a very difficult time trying to figure out when to use certain random variables. I know that a Bernoulli R.V. is used when the outcome is either a success or a failure, and the Binomial is basically performing the Bernoulli a certain number of times. But as I go through questions I dont understand why sometimes its a Bernoulli, sometimes a Hypergeometric, Poisson, Negative Binomial, Uniform distribution, Exponential etc. I cant seem to understand when to use which one.

I know how to set up the solution and what it is but I dont understand why it is a binomial.

Solution

The selection of the distribution in any scenario should be done only after all the conditions is studied. There are assumptions for each distributions which should be met.

The binomial random variable is used in this problem as it meets all the criterias of the situations.