Friday, April 6, 2012

JCCDQBHWHCB007(i) Combinatorics : Choosing with special conditions



     This sort of question has appeared in the GCE ‘A’ levels before.  For questions with special conditions, a good approach is to consider to the special conditions first.

Suggested Approach and Solution:-
 

Number of ways to choose the young player = 2C1 = 2
The captain must be in, so two vacancies have been taken up and there are 3 left.  These places must be filled from the 7 eligible other players (excluding the captain and the two youngest players).  There are   7C3 = 35  ways to do this.  The total number of ways is
          35 x 2 = 70

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