The following table represents the probability of the number of cars owned by a college student. Give your answer to at least 3 decimal places.

x	P(x)
0	0.5
1	0.34
2	0.12
3	0.04

a) Is this a valid discrete probability distribution? Select an answer No, since Σ P(x) ≠ 1 and P(x) < 0 Yes, since Σ P(x) = 1 and 0 ≤ P(x) ≤ 1 Yes, since Σ P(x) ≠ 1 and P(x) > 0 No, since Σ P(x) = 1 and 0 ≤ P(x) ≤ 1

b) Find the mean number of cars owned.  

c) Find the standard deviation of the number of cars owned.

d) Find $\displaystyle \sigma^{{2}}$ .