Negative Marking Explained: When to Guess and When to Skip

Negative marking makes many aspirants freeze. They leave questions blank that they should have attempted, or guess wildly on questions they should have left. A little arithmetic settles the question.

The expected value of a guess

Take a common scheme: +1 for a correct answer and −¼ for a wrong one, with four options.

• A completely blind guess is right one time in four. On average you gain ¼ × 1 = 0.25 and lose ¾ × ¼ = 0.1875.
• The expected gain is about +0.06 marks per guess — positive, but small, and risky across a whole paper.

Eliminate one option and everything changes

If you can confidently rule out one wrong option, you are choosing between three. Now the expected gain is ⅓ × 1 − ⅔ × ¼ ≈ +0.17 marks — nearly three times better. Rule out two options and it rises to about +0.38.

The lesson: do not guess blind, but never skip a question where you can eliminate at least one option with confidence.

When the scheme is harsher

With −⅓ negative marking on four options, a blind guess is worth exactly zero on average — pure risk with no reward. Elimination still pays. Always check the marking scheme on the instructions screen before you start.

Practise the decision, not just the content

Use your mock tests to learn your own accuracy on “50–50” questions. Your result report shows how many marks your attempted-but-wrong answers cost you. If that number is large, you are guessing too freely; if you leave many questions blank and your accuracy on attempted ones is high, you can afford to attempt more.