Question 18.11
18.11 Our favorite president. A Gallup Poll on Presidents’ Day 2011 interviewed a random sample of 1015 adult Americans. Those in the sample were asked who they regarded as the greatest U.S. president. Here are the results:
| Outcome | Probability |
| Ronald Reagan | 0.19 |
| Abraham Lincoln | 0.14 |
| Bill Clinton | 0.13 |
| John F. Kennedy | 0.11 |
| Someone else | ? |
These proportions are probabilities for the random phenomenon of choosing an adult American at random and asking her or his opinion.
(a) What must be the probability that the person chosen selects someone other than Ronald Reagan, Abraham Lincoln, Bill Clinton, or John F. Kennedy? Why?
(b) The event “I would select either Ronald Reagan or Abraham Lincoln” contains the first two outcomes. What is its probability?