||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