Question

A,B,C are three persons among 7persons who speak at a function.The number of ways in which it can be done if 'A' speaks before 'B' and 'B' speaks before 'C'
It's a permutations question​

Answer 1

Answer:

It is given that A comes before B and B comes before C.

Therefore, A comes before C.

And it is not necessary for the 3 to be together, i.e., speak exactly after one another.

The required permutation will be

7^P ^7−3

=

7^P ^ 4

7!/5!

=4(5)(6)(7)

=7.(120)

=840

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