Question

Maria has a bag with 6 red marbles , 6 blue marbles , and 4 green marbles . Without looking Maria pick one marble. She does not replace it , and she picks another one. On the first pick , Maria gets a green marble. What is the probability that she gets a red marble on her second pick ?

Answer 1

40%

The probability of her getting a red marble is the number of red marbles divided by the number of total marbles. Since she picked a green marble first, we must subtract one marble from the total number of marbles, so that the total # of marbles is 6 + 6 + 4 = 16 - 1 (green marble) = 15. Since there are 6 red marbles, our probability is 6/15 or 2/5. Converted to percentage form, this is 0.4 —> 40%