A Simple Card Guessing Game Revisited

Source abstract

A deck of cards consisting of $m$ red and $n$ black cards is given. A guess is made as to the colour of the top card, after which it is revealed and discarded. To maximise the number of correct guesses one chooses the colour corresponding to the majority of cards remaining in the deck. We determine the expected number of correct guesses with this strategy, as well as the probability of beating an opponent who uses the naive stategy of random guessing.