Flip a fair coin three times. Let X equal the number of heads and Y equal the number of tails.
a) Determine the joint probability mass function of the random vector (X,Y). b) Are X and Y independent? Explain.
I'm not sure what vector has to do with joint probability mass, my teacher never introduce vector into joint probability mass and it confusing me.
For a) i know that the joint probability mass function of X and Y would just X+Y ~ Binomial (n,p). So n would be 3 and i'm guessing p will be 1/3 . Can someone let me know if i'm doing this correctly?