6 students stand in a row. Two particular students, Minho and Jisoo, must stand next to each other. How many arrangements are possible?
Answer and explanation
Correct answer: A. 240
- Step 1: Treat the pair as one block: there are 5 units to arrange in 5! = 120 ways. Step 2. Within the block, the two can swap: 2 ways. Step 3. Total = 120 x 2 = 240. Answer: 240. Why not the others: 720: That ignores the condition. 120: That treats the pair as one unit but forgets they can swap places. 48: That treats the two as fixed in one position.
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