Answer
a) 11880
b)495
c) $\frac{1}{495}$
Work Step by Step
a) Because the order is important, we can use the permutation rule to determine the number of possibilities: $\frac{12!}{(12-4)!}=11880.$
b)Because the order is not important, we can use the combination rule to determine the number of possibilities: $\frac{12!}{(12-4)!4!}=495.$
c) By using the properties of b), and we also know that $probability=\frac{number \ of \ good \ outcomes}{number\ of\ all\ outcomes}$, therefore $P=\frac{1}{495}$.
