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

is because that a process that is exponetial distribution you can model with a binomial aproximation

like the binomial distribution you can aproximate to a normal distribution