7 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: C. 1440
- Step 1: Treat the pair as one block: there are 6 units to arrange in 6! = 720 ways. Step 2. Within the block, the two can swap: 2 ways. Step 3. Total = 720 x 2 = 1440. Answer: 1440. Why not the others: 5040: That ignores the condition. 720: That treats the pair as one unit but forgets they can swap places. 240: That treats the two as fixed in one position.
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