(a) Due to the advent of new models on the market, a car dealership has lowered the prices on last year's models to clear its holdover inventory. With prices slashed, a salesman estimates the following probability distribution of X, the total number of cars that he will sell next week:

Value of X	P(x)
0	0.05
1	0.15
2	0.35
3	0.25
4	0.20

(i) What is the probability that the salesman will sell at least three cars next week?