Four friends, (Aeesha, Emily, Julie, and Liam) had so much fun last time that they've decided to go back to the casino for the night. As they arrive each friend checks their coat at the door. There is a malfunction in the coat check system and the 4 coats are randomly returned to the 4 friends. Let X be the number of friends who receive the correct coat.

(a) Describe the range and probability mass function of X.

(b) Plot the pmf and cdf of X using R studio

(c)Find the expected value of X.