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2 votes
2 votes

1 Answer

1 votes
1 votes
Answer A)

Rooks only can go in straight line

So, 1 st rook can arrange any of $8^{2}$ ways

2nd rook can arrange in $7^{2}$

Similarly other rooks too.

Now, black rook and white rook are identical by themselves

So, black can arrange in $\frac{8^{2}.7^{2}}{2!}$

Similarly white can arrange in $\frac{6^{2}.5^{2}.4^{2}.3^{2}}{4!}$

So black and white can arrange in $\frac{\left ( 8.7\right )^{2}\left ( 6.5.4.3 \right )^{2}}{2!.4!}$

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