In a certain lottery, six numbers are randomly chosen from the set 
(without replacement). To win the lottery, a player must guess correctly all six numbers but it is not necessary to specify in which order the numbers are selected.
(a) What is the probability of winning the lottery with only one ticket?
(b) Suppose in a given week, 6 million lottery tickets are sold. Suppose further that each player is equally likely to choose any of the possible number combinations and does so independent of the selections of all other players. What is the probability that exactly four players correctly select the winning combination?
(c) Again assuming 6 million tickets sold, what is the most probable number of winning tickets?
(d) Repeat parts (b) and (c) using the Poisson approximation to the binomial probability distribution. Is the Poisson distribution an accurate approximation in this example?