victor-tsang/cardsprobabilities

Probability of playing cards

Probabilities of Cards

2 Problems

MindYourDecisions: The answers are so surprising you won't believe them, even after seeing the calculations

Problem 1

A standard deck of 52 playing cards is shuffled. The cards are turned up one by one until an ace appears. Is the next card -- the one following the first ace-- more likely to be the ace of spades or the two of clubs?

A version of this problem appeared in Sheldon Ross First Course in Probability.

Answer: same, 1/52.

Problem 2

A deck of 52 cards is placed in order. The deck is shuffled properly. How many cards, on average, do you expect to be in the same spot as before the deck was shuffled?

Answer: 1/52.