Problem #PRU-110920

Problems Methods Pigeonhole principle Pigeonhole principle (other) Algebraic methods Proof by exhaustion
 11–13  2.0

Problem

Peter has some coins in his pocket. If Peter pulls 3 coins from his pocket, without looking, there will always be a £1 coin among them. If Peter pulls 4 coins from his pocket, without looking, there will always be a £2 coin among them. Peter pulls 5 coins from his pocket. Identify these coins.