Brain Teaser


Question: Where is the Bone?

Ralph the dog can't remember where he buried his bone-under the rock, in the garden, under the porch, or under the tree. If only one of the following sentences is true, where is Ralph's bone?

  • The bone is under the rock.
  • The bone is in the garden or under the tree.
  • The bone is under the rock or under the porch.
  • The bone is not in the garden.

Answer: The bone is in the garden.

If sentence #1 is true, then sentence #3 is also true, but only one sentence can be true, so both #1 and #3 are false-the bone is not under the rock or under the porch. That leaves the garden and the tree, so let's look at sentences #2 and #4. If sentence #2 is true, then sentence #4 is false. That would leave us with just 1 true sentence, but is the bone in the garden or under the tree? We know that sentence #4 is false, so the bone must be in the garden.

Source: Lowell House, Brain Games, p.60