2. Your teacher is planning the big Midterm Exam Grading Meeting. It is tough to know what kinds of
snacks people will want so she takes a 4-sided die to the shop, going down the aisle. For each kind of snack, the teacher rolls the die. If it comes up a 4, she purchases that snack for the party. There are 40 different kinds of snacks in the aisle. Define random variable X = the number of types snacks purchased out of the 40 types available.
a) Random variable X is a binomial random variable. What is the mean of the random variable X?
b) What is the standard deviation of the random variable X?