Fact 1: Most stuffed toys are stuffed with beans.
Fact 2: There are stuffed bears and stuffed tigers.
Fact 3: Some chairs are stuffed with beans.
If the first three statements are facts, which of the following statements must also be a fact?
I: Only children's chairs are stuffed with beans.
II: All stuffed tigers are stuffed with beans.
III: Stuffed monkeys are not stuffed with beans.

Statement I: Only children's chairs are stuffed with beans.

Nothing in the facts talks about children’s chairs vs other chairs. We only know “some chairs are stuffed with beans.”

Therefore, statement I can not be concluded. 

Statement II: All stuffed tigers are stuffed with beans.

We only know “most stuffed toys are stuffed with beans,” not all stuffed toys, nor specifically tigers.

Hence, this statement also can not be concluded.

Statement III: Stuffed monkeys are not stuffed with beans.

We have no information about stuffed monkeys.

Therefore, this statement also can not be concluded. 

Therefore, none of the statements is a known fact.