Three integers are chosen from 1 to 20 without replacement. Probability that their product is even, is

Step-I:   Out of 20 integers, 3 can be selected in C3   20 ways to be product even at least one integer is even= Total-odd  =20C3−10C3R·P=20C3-10C320C3=1-10C320C3=1719=0.89