If 8 person are to sit around a table what is the probability that X and Y don't sit together

Eight person stand in a line at random. What is the probability that two person X and Y don't stand together.

4 girls and 4 boys sit in a row. Find the probability that the four girls are together

Three persons hit a target with probability 1/2,1/3 and 1/4 respectively. If each one shoot at the target once, if only one of them hits the target what is the probability that it was the first person ?

Three persons hit a target with probabilities (1/2) , (1/3) and (1/4) respectively. If each one shoots at the target once, (i) find the probaility that exactly one of them hits the target, (ii) if only one of them hits the target what is the probability that it was the first person?

A committee of 3 is to be chosen from among 10 people including X and Y. Find the probability that X and Y belong the committee

4 girls and 4 boys sit in a row. Find the probability the boys and girls sit in alternate seats.

A committee of 3 is to be chosen from among 10 people including X and Y. Find the probability that X or Y belongs the committee

By examining the chest X-ray, the probability that TB is detected when a person is actually suffering is 0.99. The probability of an healthy person diagnosed to have TB is 0.001. In à certain city, 1 in 1000 people suffers from TB. A person is selected at random and is diagnosed to have TB. What is the probability that he actually has TB?

A committee of 3 is to be chosen from among 10 people including X and Y. Find the probability that X is the committee