Lani had a box that contained: 1 blue marble, 1 green marble, 1 purple marble, 1 yellow marble, and 2 red marbles.

Question

Lani removed one marble without looking, and she recorded the result. She placed the marble back in the box and repeated the procedure one more time. What is the probability that Lani removed a red marble followed by a blue marble?

a. 1/36

b. 1/18

c. 1/3

d. 1/2

Answer 1

To remove red marble from the bag, the probability is 2/6.

To remove blue marble from the bag next, the probability is 1/6.

To find the probability to remove red then blue, we multiply the probabilities above.

What is the answer then?

Answer 2

Hi Errol,

The total number of marbles = 6

p(getting a red marble) = 2 / 6 = 1 / 3

p(getting a blue marble) = 1 / 6

p(getting a red marble followed by a blue marble) = p(getting a red marble) * p(getting a blue marble) = (1 / 3) (1 / 6) = 1 / 18

The answer is b