Two red counters, three green counters and four blue counters are placed in a row in random order. The probability that no two blue counters are adjacent is

Let $$A$$ and $$B$$ be two independent events such that the odds in favour of $$A$$ and $$B$$ are $$1: 1$$ and $$3: 2$$, respectively. Then, the probability that only one of the two occurs is

Two dices are rolled. If both dices have six faces numbered $$1,2,3,5,7$$ and $$11$$ then the probability that the sum of the number on the top faces is less than or equal to 8 is

A bag contains 50 tickets numbered $$1,2,3, ..., 50$$ of which five are drawn at random and arranged in ascending order of magnitude $$\left(x_1 < x_2 < x_3 < x_4< x_5\right)$$, then the probability that $x_3=30$ is

Five persons entered the lift cabin on the ground floor of an eight floor house. Suppose that each of them independently and with equal probability can leave the cabin at any floor beginning with the first, then the probability of all 5 persons leaving at different floors is