Question

A bag contains 7 red marbles, 8 blue marbles and 5 green marbles. If three marbles are drawn out of the bag, what is the probability, to the nearest 10th of a percent, that all three marbles drawn will be red?

Answer 1

• 3.1%

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Total number of marbles:

• 7 + 8 + 5 = 20

Probability of a first red marble:

• 7/20

Probability of a second red marble:

• 6/19

Probability of a third red marble:

• 5/18

Probability of drawing three red marbles is:

• P(r, r, r) = 7/20*6/19*5/18 = 0.0307 ≈ 3.1 %