### Question 1

** The correct answer is not in the options. Hence this question will be treated as a BONUS.** 9 coins (coloured black on one face and white on the other) are placed in a 3x3 table with all upper sides being white. Your job is to make them all black by flipping one coin at a time. But here’s the twist.

The movement you flip one coin all other coins in that row and column will be flipped as well.

What are the minimum number of moves in which you can make it all black? Following is an example:-

W W W ========================> W B W

W W W => IF WE FLIP MIDDLE ONE => B B B

W W W ========================> W B W

Answer: 5

### Comments on Question 1

### Solution

First flip coin at 1,1. Then 2,2. Then 3,3. Then 3,1. Then 1,3.