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

The total number of ways in which 3 integers can be chosen from first 20 integers is20C3 .The product of three integers will be even if at least one of the integers is even. Therefore, the required probability =1− probability that none of three integers is even=1−10C320C3=1−219=1719 .[Three odd integers can be chosen in 10C3 ways as there are 10 even and 10 odd integers.