Question

Two small squares on a chess board are chosen at random. Probability that they have a common side is,

Answer 1

Answer:

1/18

Step-by-step explanation:

In 64 squares, there are:

(1) 4 at-corner squares, each has ONLY 2 squares each having a side in common with...

(2) 6*4 = 24 side squares, each has ONLY 3 squares such that each has a side in common with...

(3) 6*6 = 36 inner squares, each has 4 squares such that each has a side in common with...

So we have the calculation:

P = (4/64)*(2/63) + (24/64)*(3/63)+ (36/64)*(4/63)

P = 1/18