Six X 's have to be placed in the square of the figure such that each row contains atleast one ' X '. In how many different ways can this be done?

Question

Six X 's have to be placed in the square of the figure such that each row contains atleast one ' X '. In how many different ways can this be done? (A) 28 (B) 27 (C) 26 (D) None of these

Tardigrade Admin · Accepted Answer

In all, we have 8 squares in which 6 ' X ' have to be placed and it can be done in 8 C6=28 ways. But this includes the possibility that either the top or horizontal row does not have any ' X '. Since, we want each row must have atleast one ' X ', these two possibilities are to be excluded. Hence, required number of ways =28-2=26

Q. Six X 's have to be placed in the square of the figure such that each row contains atleast one ' X '. In how many different ways can this be done?

28

27

26

None of these

Q. Six $X$ 's have to be placed in the square of the figure such that each row contains atleast one ' $X$ '. In how many different ways can this be done?