Strategy Guide
Negative Marking in the Drug Inspector Exam: When Should You Guess?
The UPSC Drug Inspector (CDSCO) exam deducts −1/3 of a mark for every wrong answer, with no penalty for blanks. Most aspirants play this too safe. The math says otherwise — and it's airtight.
The one rule
Never leave a question blank once you have eliminated even one option.
Blind guessing costs you nothing on average. Eliminating one option makes guessing profitable. Leaving such a question blank is the only real mistake.
The math
With 4 options and a 1/3 penalty, the expected value (EV) of attempting a 1-mark question depends only on how many options you can rule out:
| Options eliminated | Guess from | Expected marks | Verdict |
|---|---|---|---|
| 0 | 4 options | +0.000 | Break-even — no harm in guessing |
| 1 | 3 options | +0.111 | Guess — it pays off |
| 2 | 2 options | +0.333 | Guess — it pays off |
| 3 | 1 option | +1.000 | Guess — it pays off |
Read the first two rows carefully. With zero options eliminated, guessing is exactly break-even — you lose nothing by attempting. Eliminate just one option and the expected value jumps to +0.11 marks per question. Across a paper with dozens of "narrowed-down" questions, that is easily the difference between clearing the cut-off and missing it.
Why this matters more than it looks
In a 100-question paper, suppose you are unsure on 30 questions but can eliminate one option on 20 of them. Leaving all 30 blank scores 0 on those. Guessing the 20 you narrowed down adds, on average, about +2.2 marks — for zero extra risk in expectation. In a tightly-packed merit list, that is often several hundred ranks.
Practise it under real conditions
Our mock tests apply the exact −1/3 scheme and show your "guess efficiency" — how well you converted eliminations into marks.
Take a Free Mock Test →Not affiliated with UPSC or CDSCO. Marking scheme per the official notification.