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Six X 's have to be placed in the square...

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

A

28

B

27

C

26

D

29

Text Solution

Verified by Experts

The correct Answer is:
C
In all we have 9 squares in which 6 `X` have to be placed and it can be done in .^(8)C_(6)=28` ways
But his includes the possibility that either the top or lowest rows does not have any `X`. Since we want each row must have at least one `X` these two possibilities are to be excluded. Hence, requried number of ways `=28-2=26`
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