Question

A box contains seven green marbles, six blue marbles and eight orange marbles. Without looking, you choose two marbles out of the bag. What is the probability that both be green if you don’t replace the marble after the first pick?

Answer 1

Answer:

The probability is 0.1  (or 10%)

Step-by-step explanation:

The probability is the ratio of the number of favorable outcomes and the total number of possible outcomes.

The favorable count is determined as follows: we are considering Green marbles. There are 7 of them in the box, so 7 possible picks at the first draw. Since you don't replace the pick, at the next drawing there are only 6 Green ones. So for each of the 7 possible first picks, there are 6 possible second picks: number of possibilities is 7 by 6 = 42.

The total number of possible drawings, irrespective of color is determined as follows: there are 21 marbles in total at first drawing, and 20 at second. So, for each first pick there are 20 possibilities, i.e., total number is 21 by 20 = 420

The probability is therefore:

P = 42 / 420 = 1 / 10 = 0.1  (or 10%)