A corporation has 11 manufacturing plants. Of these, 7 are domestic and 4 are located outside the United States. Each year a performance evaluation is conducted for 4 randomly selected plants.

a. What is the probability that a performance evaluation will include exactly 1 plant outside the United States?

b. What is the probability that a performance evaluation will contain 3 plants from the United States?

c. What is the probability that a performance evaluation will include 2 or more plants from outside the United States?