There are 10 red buttons and 9 yellow buttons in a bag. One button is selected at random. What is the probability of NOT selecting a yellow button?
- 10 red buttons
- 9 yellow buttons
Choose the best answer.
Note
For a “not” event, count the outcomes outside the named event. This is the complement of the event.
- The complement of selecting yellow is selecting any other color.
- There are 10 non-yellow buttons out of 19 total buttons.
- So the probability is 10/19 = 10/19.
- A complement probability can also be found by doing 1 minus the probability of the event.
The correct answer is 10/19. This matches the calculation or definition, so students should focus on the reasoning rather than only memorizing the final value.