Consider a collection of envelopes consisting of 3 red envelopes​, 3 blue envelopes​, 3 green envelopes​, and 3 yellow envelopes. If three envelopes are selected at​ random, without​ replacement, determine the probability that at least one envelope is a green envelope.

Respuesta :

3/10 x 2/9 x 1/8=1/120