Class 11

Math

Co-ordinate Geometry

Straight Lines

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

- $56$
- $896$
- $60$
- $768$

No, we have selected any one white square, there are eight black squares lying in the same column or row so out of $32−8=24$ black squares

We need to select one black square that is $24 C_{1}$

So, if both squares selected then our work is done

Hence it is in $32×24=768$ ways.