Topics:

• Counting permutations when there are indistinguishable elements

• Discrete Random Variables

Here are my notes on discrete random variables:

MAT2572RVsAndTheirPDsNotesDiscreteCase

Homework will be in a separate post.

If you are defining a random variable, the important thing is that you should be able to look at any outcome in the sample space and say what  number goes with that outcome.

I could  define a different random variable for the example of rolling two balanced dice, as follows:

Y = the number of even numbers that show on the dice.

Then for the outcome (1,1), Y=0, and for the outcome (2,3), Y=1. The value of Y depends on the outcome of the random experiment.

The possible values of Y are 0, 1, and 2

Exercise: find the pdf for Y