There are three versions of a board game released - version 1, version 2, and version 3. The versions are distributed equally and evenly among all potential sellers of board games.
a. What is the probability of someone potentially purchasing each of the versions of the board game, if purchased at random?
b. What is the probability that someone would purchase exactly two of version 1 if they were to purchase 10 versions of the board game randomly?
c. What is the probability that someone would obtain more than 2 of version 2 if they were to buy 7 of the board games at random?
d. Determine the mean and variance for the number of Version 3 that someone would expect to get if they were to purchase 18 of the board games at random.