find the probability that both are red.

Question

Suppose a jar contains 5 red marbles and 32 blue marbles. If you reach in the jar and pull out 2 marbles at random without replacement, find the probability that both are red. Round your answer to three decimal places.

Answer 1

The total number of marbles is 5 + 32 = 37. You select a marble 2 times.

The 1st time you pick a marble, the probability of selecting red is 5/37.

Since there is no replacement, now we only have 4 red marbles to choose from a total of 36 marbles. So the second time the probability is 4/36.

Now we multiply the 2 answers:

(5/37) * (4/36) = 0.015015, or rounded to 3 decimal places, 0.015.