Question

a bag contains 11 orange cubes and 9 black cubes once a cube is picked it is not replaced what is the probability of choosing 2 black cubes

Answer 1

18/95

Explanation:

At first, there are 20 cubes, 9 of which are black. The probability that the first cube is black is P = 9/20.

After the first cube is selected, there are 19 cubes left, 8 of which are black. The probability that the second cube is black is P = 8/19.

The total probability is:

P = (9/20) (8/19)

P = 18/95