📐 Mathematics · Probability (Class 11) · JEE

The letters A, B, C, D are arranged at random in a row. The probability that A comes before B is:

Answer: 1/2.

Correct answer: B. 1/2

Explanation: By symmetry A is before B in exactly half the arrangements, so the probability is 1/2.

Concept context

Random experiments, sample space, events, and the axiomatic approach to probability