A bag contains 7 green and 5 black balls. 3 balls are drawn at random one after the other. If the balls are not replaced, then the probability of all three balls being green is

If $$x$$ is chosen at random from the set $$\{1,2,3, 4\}$$ and $$y$$ is chosen at random from the set $$\{5,6,7\}$$, then the probability that $$x y$$ will be even is

The discrete random variables $$X$$ and $$Y$$ are independent from one another and are defined as $$X \sim B(16,0.25)$$ and $$Y \sim P(2)$$. Then, the sum of the variance of $$X$$ and $$Y$$ is

If 6 is the mean of a Poisson distribution, then $$P(X \geq 3)=$$