Probability & Statistics : Frequency Function, Expected Value (Mean) & Variance

A game is played on a board marked off into a line of four squares, as in the figure below. A player starts on the square numbered 2. On each turn, a six-sided die is thrown, and the players moves one square to the left if the die comes up 5 or 6, and one square to the right otherwise. The game ends when the player reaches either end of the board (square 1 or square 4).

|Square 1|Square 2|Square 3|Square 4|
(The "|"'s are not absolute values, they are "boxes."

a/ Let X be the numbers of moves until the game ends. Find the frequency function of X.
b/ Find E(X).
c/ Find Var(X). (You can leave the expression as a series.)