Alex and Fatima both randomly guess all of the answers on a four-question true/false quiz. Because their guesses are random, each question has an equal chance of being correct or incorrect. After the quiz, they try to predict their grades.
Alex thinks that the probability of getting correct answers on the first three questions is equal to the probability of getting exactly three questions correct overall. Fatima disagrees. She thinks that the probability of getting three questions correct overall is greater.
The sample space of possible outcomes is listed below. C represents a correct answer, and I represents an incorrect answer.
**Who is correct, Alex or Fatima?**
[[☃ radio 1]]
| | | |
- | - | - | - |
C C C C | C C C I | I I C I | C I I C
I C C C | I I I I | I I I C | I I C C
C I C C | C I I I | C C I I | I C I C
C C I C | I C I I | C I C I | I C C I