r1, r2, r3 ∈ {1, 2, 3, 4, 5, 6}
r1, r2, r3 are of the form 3k, 3k + 1, 3k + 2
Required probability = 3! * 2C1 * 2C1* 2C1 / 6*6*6
=6*2*2*2/6*6*6
=2/9 (c)
I THINK THIS SHOULD BE RIGHT WHTS THE ANSWER?