what is the probability that a red or green marble will be selected from a bag containing 9 red marbles, 7 green marbles, and 11 yellow marbles if one is selected randomly ? Help

Respuesta :

P(red) = 9/(9 + 7 + 11) = 9/27 = 1/3
P(green) = 7/27

P(red or green) = 1/3 + 7/27 = 16/27