Question

Brianna has a bag of marbles that are all the same size. Of all the marbles in the bag, there are 6 red, 7 white, 3 black, and 4 green marbles.





Write a probability model for this experiment, and use the probability model to predict how many times Brianna would pick a green marble if she chose a marble 50 times. Give the probabilities as simplified fractions.



Drawing a green marble

Answer 1

Total marbles = 6 + 7 + 3 + 4 = 20.

Probability model (simplified fractions):
- P(red) = 6/20 = 3/10
- P(white) = 7/20
- P(black) = 3/20
- P(green) = 4/20 = 1/5

If Brianna draws 50 times (with replacement so probabilities don’t change), the expected number of green marbles = 50 × P(green) = 50 × 1/5 = 10.

So you would predict she draws a green marble 10 times.