A fair number cube has faces numbered 1 to 6. What is the probability of rolling a number that is not prime?
- Possible outcomes: 1, 2, 3, 4, 5, 6
- Use the meaning of the event to test each option.
Choose the best answer.
Note
Use the key probability or statistics idea first, then check the arithmetic carefully.
- A fair number cube has 6 equally likely outcomes: 1, 2, 3, 4, 5, and 6.
- The outcomes that match the event are 1, 4, 6, so there are 3 favorable outcomes.
- Therefore, the probability is 3/6 = 1/2.
The correct answer is 1/2. This matches the calculation or definition, so students should focus on the reasoning rather than only memorizing the final value.