SuccessfiedNegative marking: should you guess?
A guess is worth it only when your chance of being right beats the break-even point. Ruling out even one option changes everything.
This exam's negative marking is awaiting official confirmation — adjust the penalty yourself.
How it works
If a right answer gives m marks and a wrong one costs n, a guess that is right with probability p is worth p×m − (1−p)×n on average. It pays only when p is above n ÷ (m + n). For example, with +1/−0.25 you need to be right 20% of the time. A blind guess among four options is right 25% of the time, so it is only slightly positive on average; ruling out one option lifts you to 33%.
Your own reports show how often your "50-50" and "Guess" answers were actually right — use that number, not a feeling.