Q7 PERMUTATION AND COMBINATION

In how many ways is it possible to choose a white square and a black square on a chessboard so that the squares must not lie in the same row or column?

There are 32 white and 32 black squares on the chessboard

Number of ways of choosing the white square = 32

When a white square is selected, we cannot select the black square lying on the row or column of the white

Square. We have 8 such black squares for every white square selected.

Hence we have 32-8=24 black squares which can be selected for every white square selected

Total number of possibilities= 32 × 24= 768.

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