“Reasonable answer” marks are one of the most misunderstood features of IB Maths AI. Many students assume these marks are consolation points or awarded only when something has gone wrong. In reality, they are a deliberate reward for good mathematical thinking, even when answers are approximate.
IB Maths AI deals heavily with real-world contexts, where exact answers often do not exist. Estimation, modelling, interpolation, and sampling all involve uncertainty. In these situations, IB recognises that insisting on exact numerical precision would be unrealistic. Instead, they reward students who produce values that make sense given the context and method used.
A reasonable answer is not a guess. It is a value that follows logically from the student’s working and assumptions. IB examiners look at whether the number fits the situation, has the correct order of magnitude, and aligns with the interpretation given. A slightly inaccurate value with strong reasoning often earns more marks than a precise value with no explanation.
These marks also protect students from minor errors. If a student makes a small arithmetic slip but continues logically and interprets their result correctly, reasonable answer marks allow examiners to credit understanding rather than punish a single mistake. This reflects the AI philosophy: maths as thinking, not just computation.
Students often lose these marks by second-guessing themselves. They erase sensible estimates because the number “looks ugly” or doesn’t match expectations. IB explicitly accepts messy decimals, awkward values, and approximations, as long as they are justified.
Reasonable answer marks also encourage sense-checking. Students who pause to ask whether an answer is too large, too small, or unrealistic demonstrate control. Examiners reward this habit because it mirrors real analytical work.
The biggest mistake students make is assuming that only one exact answer is acceptable. In many AI questions, multiple reasonable answers exist. What matters is the quality of reasoning, not numerical perfection.
Once students realise that reasonable answer marks are there to help them, not trap them, their confidence improves. They stop chasing perfection and start focusing on clarity, logic, and interpretation — exactly what IB wants.
Frequently Asked Questions
What counts as a reasonable answer?
A value that makes sense in context, follows from your method, and is interpreted correctly.
Can two students get different answers and both be correct?
Yes, as long as both answers are reasonable and well-justified.
Do I need to say “this is reasonable” explicitly?
Not usually. Clear working and sensible interpretation show this naturally.
RevisionDojo Call to Action
AI Maths rewards thinking, not flawless decimals. RevisionDojo is the best platform for IB Maths AI because it trains students to estimate confidently, justify answers clearly, and secure reasonable answer marks consistently. If you’re losing marks chasing perfection, RevisionDojo helps you focus on what IB actually rewards.
