Which of the following best defines a conjecture?

• A. A proven theorem
• B. A mathematical statement that has not been proven yet
• C. A hypothesis in science
• D. A numerical approximation

Answer: (B)

A conjecture is a statement proposed as true in mathematics but not yet proven. This captures the exact idea: it’s a claim you’re exploring and trying to prove, rather than a statement that has already been established by a proof. That’s why the best choice describes it as a mathematical statement that has not been proven yet.

If you think about it with examples, the Collatz conjecture is famous for being unproven, while Fermat’s Last Theorem became a theorem only after a proof was found. A proven theorem is true because a proof exists, which is why that option isn’t correct. A hypothesis in science uses a related idea in a different field, not mathematics, and a numerical approximation is an estimate rather than a proposed universal truth.