. There are 5 cars in a car dealer and 5 keys. The sales person doesn't know which key is for which car. If assign 5 keys to each car, which one below is impossible as the number of cars that will have the right key?
only 4 cars can not have right key... because, if that is the case then there is only one wrong car-key left, there has to be another car-key which is not a right combination....