GATE 2026 Chemical Engineering, Q34 · Mathematics
The correct answer is 0.5.
Question
An experiment is performed by rolling an unbiased die once. Event A: the outcome is a prime number. Event B: the outcome is an odd number less than 4. The conditional probability of A given B, denoted by P(A|B), is ______ (rounded off to one decimal place).
Official answer: 0.5
Why
GATE 2026 official key: 0.5. For equally likely outcomes, P(A|B) = |A∩B|/|B|. Here A={2,3,5} (primes) and B={1,3} (odd, <4), so A∩B={3}, giving P(A|B) = 1/2 = 0.5.
Explanation cross-checked for consistency. Final answer matches the official IIT answer key.