PMF FOR THE BINOMIAL DISTRIBUTION
Suppose that a fair die is rolled 10 times. What is the probability of throwing exactly two sixes?
You can answer the question using the dbinom function:
> dbinom(2, 10, 1/6)  0.29071
PMF FOR THE POISSON DISTRIBUTION
The number of sandwhich ordered in a restaurant on a given day is known to follow a Poisson distribution with a mean of 20. What is the probability that exactly eighteen sandwhich will be ordered tomorrow?
You can answer the question with the dpois function:
> dpois(18, 20)  0.08439355
PDF FOR THE NORMAL DISTRIBUTION
To find the value of the pdf at x=2.5 for a normal distribution with a mean of 5 and a standard deviation of 2, use the command:
> dnorm(2.5, mean=5, sd=2)  0.09132454