In how many ways is it possible to select two white squares so that they lie in the same row or same column on a 8 x 8 Chessboard
1)12
2)48
3)96
4)60
5)100
1)12
2)48
3)96
4)60
5)100
you need to find out how many are available for the first pick - 8*8=64 squares - and 1/2 of them are white so there are 32 white squares. So for the first piece there are 32 ways to pick the first piece - then for the second piece there are 3 additional whites in each row and 3 additional whites in each column for 6 total pieces you could pick.
you multiply 32 *6 to get 192. Now because order doesn't matter you must divide by the number of pieces you are picking factorial (to eliminate all of the combinations that are essentially the same) - you are picking 2 pieces so you divide 192 by 2! - which is 96. Answer C.
