Q21 Eleven books, consisting of five Engineering books, four Mathematics books and two Physics books, are arranged in a shelf at random. What is the probability that the books of each kind are all together?

Q22 In a race, the odds in favour of cars P, Q, R, S are 1 : 3, 1 : 4, 1 : 5 and 1 : 6 respectively. Find the probability that one of them wins the race.

Q23 Tickets numbered 1 to 30 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?

Q24 Three students appear at an examination of Mathematics. The probability of their success are 1/3, 1/4, 1/5 respectively. Find the probability of success of at least two.

Q25 Seven white balls and three black balls are randomly placed in a row. Find the probability that no two black balls are placed adjacently to each other.

Q26 A speaks the truth in 75% of cases and B in 80% of cases. In what percent of cases are they likely to contradict each other in narrating the same event?

Q27 Find the probability of getting a numbered card when a card is drawn from the pack of 52 cards.

Q28 Two cards are drawn from the pack of 52 cards. Find the probability that both are diamonds or both are kings.

Q29 A problem is given to three persons P, Q, R whose respective chances of solving it are 2/7, 4/7, 4/9 respectively. What is the probability that the problem is solved?