Three integers are chosen at random from the first 20 integers. The probability that their product is even is:

17/19

For product to be even, there should be atleast one even no. amongst the three chosen numbers.

Total no. of favorable groups = n(1 even, 2 odd) + n(2 even, 1 odd) + n(3 even)

$={^{10}C}_1.{^{10}C}_2+{^{10}C}_2.{^{10}C}_1+{^{10}C}_3=$