A student makes a trip once per day to the store, and he always buys a snack. The student eats the snack 70% of the time, but the other 30% of the time, his roommate eats it first.
a. During a period of four days, the student keeps track of whether he gets to eat his snack. What is the sample space of possible outcomes?
b. Let X be the number of times, within the four day period, that he gets to eat his snack. What is the mass of X?
c. What is the CDF of X?