Answer: 1/3.
- A 2/5
- B 1/2
- C 1/3
- D 1/6
Correct answer: C. 1/3
Explanation: Treating the pair as one block gives 5!·2! = 240 arrangements out of 6! = 720, so P = 240/720 = 1/3.
Concept context
Random experiments, sample space, events, and the axiomatic approach to probability