A bag contains 7 red marbles, 8 blue marbles and 3 green marbles. If two marbles are drawn out of the bag, what is the exact probability that both marbles drawn will be red?

Answer 1

To find the probability of drawing two red marbles, we need to calculate the probability of drawing a red marble on the first draw and then another red marble on the second draw.

The probability of drawing a red marble on the first draw is 7/18 (since there are a total of 18 marbles in the bag and 7 of them are red).

After drawing 1 red marble, there will be 6 red marbles left out of a total of 17 marbles in the bag. So, the probability of drawing a red marble on the second draw is 6/17.

Therefore, the probability of drawing two red marbles is (7/18) * (6/17) = 42/306 = 7/51.

Therefore, the exact probability that both marbles drawn will be red is 7/51.