Question : Three integers are chosen at random from the first 20 integers. The probability that their product is even is
(A) 2/19
(B) 3/29
(C) 17/19
(D) 4/29
Answer : option
Solution :
The total number of ways in which 3 integers can be chosen from first 20 integers is 20C_{3}. The product of three integers will be even if at least of the integers is even.
Therefore, the required probability is,
= 1 – probability that none of the three integers is even
= 1-\dfrac{10C_{3}}{20C_{3}}=1-\dfrac{2}{19}=\dfrac{17}{19}