1. The problem statement, all variables and given/known data Cards from a standard deck of 52 playing cards are laid face up one at a time. If the first card is an ace, the second card is an 2, the third card is a three, ..., the 13th card is a king, the 14th is an ace, etc. we call it a "match." The 13n+1th card does not need to be any particular ace, it just needs to be an ace. Find the expected number of matches that occur. 2. Relevant equations 3. The attempt at a solution I let the random variable X represent the total number of matches. So Xi=1 if the ith card is a match, and 0 if it is not a match. Then I summed over the all the cards from 1 to 52. The thing that I was having trouble calculating was P(Xi=1). It seems like on any given trial there is a 4/52 chance of getting a match, but this seems oversimplified.