In a game of monopoly, a player cannot start until she throws a "double" with a set of two six-sided dice, i.e. both dice must show the same number (from 1 to 6) uppermost when tossed.

a) State the form of the probability distribution of

, the number of unsuccessful turns a player has before she manages to throw a "double".

--> This is the answer to the function but I'm confused about why:

Is the exponent

only at the probability for unsuccessful rolls because there should never be more than one roll of success?

b) Find

If X is for the number of unsuccessful turns made before a success, how do you calculate a "greater than or equal to" value if no total number of trials is given?

c) Find