The question given below contains three elements. These elements may or may…
2024
The question given below contains three elements. These elements may or may not have some inter linkage. Each group of elements may fit into one of these diagrams at (A), (B), (C), (D) and/or (E). You have to indicate the group of elements which correctly fits into the diagrams. Which of the following diagrams indicates the best relation between dogs, pet animals and animals ?
Attempted by 2 students.
Show answer & explanation
In a Venn-diagram classification question, each group is drawn as a circle. "All X are Y" is shown by drawing X's circle completely inside Y's circle. "Some X are Y" is shown by drawing the two circles so that they partially overlap: the shared region stands for the members common to both groups, while each circle still has a part sticking out for members that belong to only one group. Two groups with no members in common are drawn as separate, non-touching circles.
Here the three terms are Dogs, Pet Animals, and Animals. This question does not give an explicit logical statement to diagram -- instead, you have to draw on general, real-world knowledge of how these three categories relate. Every dog is an animal, and every pet animal is also an animal, so both the Dogs shape and the Pet Animals shape must be drawn completely inside the Animals shape. In the real world, some dogs are kept as pets, though not every dog is a pet (many are strays or wild), and not every pet animal is a dog (cats, birds, fish, etc. are pets too). This partial overlap between Dogs and Pet Animals -- some members shared, some not, in both directions -- calls for two shapes that intersect each other, rather than one containing the other or the two staying fully apart. So the diagram needed is one large outer shape for Animals, with two smaller shapes for Dogs and Pet Animals drawn inside it, overlapping each other.
Checking every region of that diagram against the statement confirms it: the overlapping sliver represents dogs that are also pet animals (matching "some dogs are pet animals"); the non-overlapping part of the Dogs circle represents dogs that are not pets; the non-overlapping part of the Pet Animals circle represents pets that are not dogs (for example, cats); and the space inside the Animals circle but outside both smaller circles represents animals that are neither dogs nor pets (for example, lions). Every region corresponds to a real group, confirming that a large circle enclosing two overlapping smaller circles is the diagram that correctly captures all three facts.
Why the other diagrams don't fit:
A layout where two circles cross each other directly and a third circle is drawn fully apart from them fails to place any group entirely inside another, so it cannot show that every dog and every pet animal is an animal.
A layout where two smaller circles sit inside the larger circle without touching each other would mean no dog is ever a pet animal, which contradicts "some dogs are pet animals."
A layout where one smaller circle sits entirely inside another smaller circle, with a third circle drawn fully apart from both, would mean every member of one group automatically belongs to the other with no partial distinction, and treats the third group as having no connection at all to the first two -- neither matches the given statement.