Total number of ways of selecting 3 square =64C3 Total number of ways of selecting 2 square of one colour and other square of different colour =(2 white, 1 black) or ( 1 white, 2 black) =32C2⋅32C1+32C1⋅32C2 =2⋅32C2⋅32C1 Required Probability =‌