George buys six lottery tickets for $2 each. In addition to the grand prize, there is a 20% chance that each lottery ticket gives a prize of $4. Assume that these tickets are not grand prize winners.

a. What is the probability that the tickets are winners more than the average that George expected?

b. What is the probability that none of the tickets are winners?

c. What is the probability that at least one of the tickets is a winner?