In: Math
Your friend has chosen a card from a standard deck of 52 playing cards and no one knows the card except himself. Now you have to guess the unknown card. Before guessing the card, you can ask your friend exactly one question, the question must be either Q1, Q2 or Q3 below:
Q1. whether the chosen card is a king (K)?
Q2. whether the chosen card is a spade (♠)?
Q3. whether the chosen card is the king of spades (K♠)? Your friend will answer truthfully. What question would you prefer to ask so that it is more helpful to make a correct guess? Justify your answer.