favorable should mean that you want to play this game, that you EXPECT to win more than you lose, positive expectation.
DO WE lose a dollar if we slect a Gold?
I assume so, otherwise clearly the expectation is positive, since the rv is nonnegative.
You can write out all the possibilties since there are only 5 balls.
I would think along the lines of how many balls can we pick.
The game can end in one selection with the first ball being silver.
The random variable, I assume is your winnings.