Logic

Dogs on Trial

Someone's dog goes around the neighborhood every night getting into people's garbage pails and making a mess. Some of the neighborhood kids say they know what the guilty dog looks like, but the culprit strikes at night, so it's hard to see. Each of the four witnesses has one and only one detail right, and each detail is described correctly by only one witness.

Dan says the dog is white, fluffy, wears a red collar, and has a long tail.
Karen says the dog is black, has short hair, wears a red collar, and has a long tail.
Max says the dog is brown, has long, silky hair, wears a blue collar, and has a long tail.
Emma says the dog is spotted, fluffy, wears a red collar, and has a short tail.

Can you correctly describe the guilty pooch?

The dog is white, has short hair, wears a blue collar, and has a short tail.

To arrive at the answer, begin by making a chart like the following:

 color hair collar tail Dan white fluffy red long Karen black short red long Max brown long & silky blue long Emma spotted fluffy red short

Next, cross out the details in each column that are repeated. (only one detail is described correctly by each witness: the dog can't be fluffy, can't wear a red collar, and can't have a long tail.) Now you have all the information you need:

The dog wears a blue collar and has a short tail.

The dog must be white, because Dan is wrong about the hair, the collar, and the tail, and he has to be right about one detail.

Karen, Max, and Emma are wrong about the dog's color; therefore the dog must have short hair, because Emma has to be right about one detail.