Multiple choice

There are eight question papers, then the number of ways that the best and the worst are always together is

  1. $6! 2!$
  2. $7! 2!$
  3. $\dfrac{8!}{2!}$
  4. $8! 2!$
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B Correct answer
Explanation

Treat the best and worst as one unit. We have 7 units to arrange (6 others + 1 pair). They can be arranged in 7! ways, and the pair can be arranged in 2! ways. Total = 7! * 2!.

AI explanation

By treating the best and worst papers as a single tied unit, the 8 total papers become 7 distinct units to arrange. These 7 units can be ordered in 7! different ways. Because the best and worst papers can be swapped in 2! ways within their tied unit, the total number of arrangements is 7! * 2!.

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