Same here
E(X) = 2/90*20$ + 6/90*10$ + 20/90*5$ - 62/90*4$ = -8/15$
question:
We have 10 marbles in a bag: 5 red, 3 blue, 2 yellow. We randomly pull two marbles without replacement. If we pull two yellow marbles, we receive $20. If we pull two blue marbles, we receive $10. If we pull two red marbles, we receive $5. If we pull two marbles of different colors, we pay $4. Find the expected value of this game.
I won't try to explain how but I came up with: -8/15
Anyone else?