There are 10 white marbles and 3 orange marbles in a bag. One marble is selected at random. What is the probability of NOT selecting a white marble?
- 10 white marbles
- 3 orange marbles
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 white is selecting any other color.
- There are 3 non-white marbles out of 13 total marbles.
- So the probability is 3/13 = 3/13.
- A complement probability can also be found by doing 1 minus the probability of the event.
The correct answer is 3/13. This matches the calculation or definition, so students should focus on the reasoning rather than only memorizing the final value.