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COMEDK2023MathematicsProbability

A five-digits number is formed by using the digits 1,2,3,4,5 with no repetition. The probability that the numbers 1 and 5 are always together, is

Options

  1. A2 5
  2. B1 5
  3. C3 5
  4. D1 4

Correct answer

A. 2 5

Step-by-step solution

The total number of possible five-digit numbers =5 ! The total number of possible five-digit numbers in which 1 and 5 are always together =2 4 ! Required probability = 2 4 ! 5 ! = 2 4 ! 5 4 ! = 2 5

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