Question

A meeting is to be addressed by 6 speakers, A, B, C, D, E and F. In how many ways can the speakers be ordered if:

A) B must come second?

B) B must immediately follow A?

Answer 1

6 speakers : A,B,C,D,E and F

A) B must come second : Remining postitions 5 : 5 Speakers

Number of ways 5 speakers can be ordered = 5! = 5 x 4 x3 x 2 x1= 120 ways

Number of ways the speakers be ordered if:B must come second =120

B)

B must immeditely Follow A :

I.e The order AB shall always be maintained : Let X = AB be considered as one speaker

Now the speakers : C,D,E, F and X

Number of speakers = 5

Number of ways 5 speakers can be ordered = 5! = 5 x 4 x3 x 2 x1= 120 ways

Number of ways the speakers be ordered if B must immeditely Follow A =120