Source: http://datagenetics.com/blog/october42014/index.html
I have a question about this gambling game where you have a standard deck of 52 cards facing down 26 black and 26 red.
The rules are you draw one card at a time at random.
For each black card you draw, you earn 1 dollar, and for each red card you draw, you lose 1 dollar.
How can I compute the current expected value of the game?
For example in the link above, they offer a formula which I cannot seem to figure out. For example in the Four Apples up on top section computes 1 dollar (1 Black, 2 Red left) and 33 cents (2 Red, 1 Black left) for each branch. How were these computed?