A corporation has 11 manufacturing plants. Of these, seven are domestic and four 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?