<Dl> <Dd> 2. b) The three remaining coins are heavier . In this case you now know that one of those three coins is the odd one out and that it is heavier . Take two of those three coins and weigh them against each other . If the balance tips then the heavier coin is the odd one out . If the two coins balance then the third coin not on the balance is the odd one out and it is heavier . </Dd> </Dl> <Dd> 2. b) The three remaining coins are heavier . In this case you now know that one of those three coins is the odd one out and that it is heavier . Take two of those three coins and weigh them against each other . If the balance tips then the heavier coin is the odd one out . If the two coins balance then the third coin not on the balance is the odd one out and it is heavier . </Dd> <Dl> <Dd> <Dl> <Dd> 2. c) The three remaining coins balance . In this case you just need to weigh the remaining coin against any of the other 11 coins and this tells you whether it is heavier, lighter, or the same . </Dd> </Dl> </Dd> </Dl> <Dd> <Dl> <Dd> 2. c) The three remaining coins balance . In this case you just need to weigh the remaining coin against any of the other 11 coins and this tells you whether it is heavier, lighter, or the same . </Dd> </Dl> </Dd>

You have nine coins and a balance scale