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Question

25 books are placed at random on a shelf. The probability that a particular pair of books shall be always together is:

This question was previously asked in
SSC CGL 2024 (Tier-I) Previous Year Paper (17-Sep-2024) (Shift 3)
The correct answer is

2/25

If we treat the particular pair of books as a single entity, then the number of possible arrangements of the 24 entities (23 books + the pair) is 24!. Within the pair, the books can be arranged in 2! ways. Therefore, the probability of this specific pair being together is 2/25.

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Similar Questions

  1. Suppose a die is thrown four times and 5, 3, 5, 3 are obtained, respectively. Then the empirical probability of getting 5 is:

  2. For any two events A and B in sample space S, which of the following options is NOT true?

  3. If a biased coin is tossed 10 times, out of which head is obtained 3 times, then what is the probability of getting head on the 11th toss?

  4. Find the probability that there may be 53 Sundays in a leap year.

  5. On rolling of a die, the events E1 (getting an even number) and E2 (getting an odd number) are:

  6. If a fair six-sided die is tossed twice and the tosses are independent, then the probability of getting a 5 on both tosses is:

  7. Die I has 4 red and 2 white faces and die II has 2 red and 4 white faces. A coin is flipped once. If head appears, the game continues by flipping die I, and if tail appears, then die II is used. The probability of getting a red face at any throw is:

  8. As the sample size increases, empirical probability:

  9. 'p' is the probability that a man aged x years will die in a year. A man aged x, A₁ will die in a year and will be the first to die.

  10. If P(A ∪ B) = 5/9, P(A ∪ B̅) = 13/27, P(A) = 11/18, then the odds against the event B are:


Important Questions from Probability

  1. The probability of being 53 Sundays in year 2020 is-

  2. Three dice are thrown randomly. The probability of coming 3 in at least one die is

  3. The probability of having 53 Tuesdays in an ordinary year is:

  4. Two dice are thrown simultaneously The probability of getting the sum 2 or 8 or 12 is

  5. If two balanced dice are tossed once, the probability of the event, that the sum of the integers coming on the upper sides of the two dice is 9, is

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