Step-by-step explanation:
With each draw, the probability of selecting a green marble is 2/3 and the probability of selecting a yellow marble is 1/3.
To pick two of the the same color, they can either pick green twice or yellow twice.
P = (2/3)(2/3) + (1/3)(1/3)
P = 5/9
To pick two different colors, they can either pick green first then yellow, or yellow first then green.
P = (2/3)(1/3) + (1/3)(2/3)
P = 4/9
Expected value for Derek is:
D = (5/9)(-1) + (4/9)(1)
D = -1/9
The expected value for Mia is:
M = (5/9)(1) + (4/9)(-1)
M = 1/9