Multiple choice

If eight persons are to address a meeting, then the number of ways in which a specified speaker is to speak before another specified speaker is?

  1. $2520$
  2. $20160$
  3. $40320$

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total permutations of 8 people is 8!. In half of these, one specific person is before another. 8! / 2 = 40320 / 2 = 20160.

AI explanation

The total number of ways to arrange 8 persons without any restrictions is 8!, which equals 40320. For any given arrangement, the probability that one specified speaker speaks before another specified speaker is exactly 1/2. Multiplying the total arrangements by this probability gives 40320 / 2, which equals 20160.

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