In the following figure, the shaded region represents the system of constraints:

On average, one out of 10 persons is busy. If six persons are selected at random, then the probability that at least 5 of them will be busy is...

If a discrete random variable $X$ takes the values $1, 2, 3, 4$ such that $2P(X = 1) = 3P(X = 2) = P(X = 3) = 5P(X = 4)$, then $P(X = 4) = \ldots$

Three numbers are chosen from 1 to 30. The probability that minimum is 10 and maximum is 26 is _______