9 PERSONS ENTER A LIFT FROM THE GROUND FLOOR OF A BUILDING WHICH STOPS IN NINE FLOORS.(EXCLUDING GROUND FLOOR). IF IT IS KNOWN THAT THE PERSONS WILL LEAVE THE LIFT IN GROUPS OF 2, 3, 4 IN DIFFERENT FLOORS.IN HOW MANY WAYS CAN THIS HAPPEN
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floors= 9
floor where the person exist = 3
9C3 = 9x 8x 7/ 3x2
= 84 ways
lets say there are 3 groups
A= 2 persons
B = 3 persons
C = 4 persons
these floors can exist in 3! ways or 6 ways
total number of ways = 6 x 84 = 504 ways
ways in which group A B C can be formed ;
9C2 x 7C3 x 4C4 = 1260 ways
the required number of ways = 1260 x 504
= 635040
floor where the person exist = 3
9C3 = 9x 8x 7/ 3x2
= 84 ways
lets say there are 3 groups
A= 2 persons
B = 3 persons
C = 4 persons
these floors can exist in 3! ways or 6 ways
total number of ways = 6 x 84 = 504 ways
ways in which group A B C can be formed ;
9C2 x 7C3 x 4C4 = 1260 ways
the required number of ways = 1260 x 504
= 635040
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