Dr. Johnson puts three coins on the table: a gold coin, a silver coin, and a copper coin. He then asks his nurse to say a sentence. If she says a truthful sentence, she gets a coin (doesn’t matter which). If her sentence is false, she gets nothing. What sentence should the nurse say to get a golden coin?
[su_spoiler title=”See the answer” style=”fancy”]
Answer: The nurse should say: “You will give me neither a copper nor a silver coin”. If this statement is true, then she gets a golden coin. If this statement is false, she should get two coins (copper and silver) which contradicts to the original conditions (she should get nothing if the statement is false). Her statement must be true.