A corporation has 25 manufacturing plants. Of these, 18 are domestic and 7 are located outside the United States. Each year a performance evaluation is conducted for 4 randomly selected plants.
a. What is the probability that the evaluation will include no plants outside the country?
b. What is the probability that the evaluation will include at leat 1 plant outside the country?
c. What is the probability that the evaluation will include no more than 1 plant outside the country?