Subject
Quantitative Aptitude
Topic
Probability
fifteen persons are sitting around a circular table facing the centre. What is the probability that three particular persons sit together ?
fifteen persons are sitting around a circular table facing the centre. What is the probability that three particular persons sit together ?
ক)
3/91খ)
2/73গ)
1/91ঘ)
3/73Explanation
In a circle of n different persons, the total number of arrangements possible = (n - 1)! Total number of arrangements = n(S) = (15 – 1)! = 14 ! Taking three persons as a unit, total persons = 13 (in 4 units) Therefore no. of ways for these 13 persons to around the circular table = (13 - 1)! = 12! In any given unit, 3 particular person can sit in 3!. Hence total number of ways that any three person can sit = n(E) = 12! X 3! Therefore P (E) = probability of three persons sitting together = n(E) / n(S) = 12! X 3 ! / 14! = 12!x3x2 / 14x13x12! = 6/14x13 = 3/91Related questions
A bag contains 6 white and 4 black balls .2 balls are drawn at random. Find the probability that they are of same colour.A problem is given to three students whose chances of solving it are 1/2, 1/3 and 1/4 respectively. What is the probability that the problem will be solved?Three fair coins are tossed simultaneously. Find the probability of getting more heads than the number of tailsTwo cards are drawn at random from a pack of 52 cards.what is the probability that either both are black or both are queen?The probabilities that a student will receive an A, B, C or D grade are 0.4, 0.3 , 0.2 and 0.1 respectively. Find the probability that a student will receive Atleast B grade.Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5 ?There are 4 women and 4 men sitting in a waiting room for job interview. If two of the applicants are selected at random, what is the probability that both will be women?Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?