If four squares are chosen at random on a chess board. If the probability that they lie on a diagonal line is , then the value of
must be
The number of ways
The chess board can be divided into two parts by a diagonal line . Now, if we begin to select four squares from the diagonal
, then we can find number squares selected
and similarly number of squares for the diagonals chosen parallel to
Total favourable ways
Required probability
Hence option 4 is correct.
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