The Ace AirLines has a policy of overbooking flights. The random variable x represents the number of passengers who cannot be boarded because there were more passengers that seats.

x P(x)
0 0.061
1 0.132
2 0.255
3 0.345
4 0.207

a)Is this a probability distribution? How do you know?
b)What is the mean number of passengers left at the gate?
c)What is the variance of the number of passengers left at the gate?
d) What is the standard deviation of the number of passengers left at the gate?