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COMEDK · Maths · 36. Probability

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

  1. A \(\dfrac{1}{5}\)
  2. B \(\dfrac{1}{4}\)
  3. C \(\dfrac{2}{5}\)
  4. D \(\dfrac{3}{5}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\dfrac{2}{5}\)

Step-by-step Solution

Detailed explanation

The total number of ways to form a five-digit number using the digits \(1, 2, 3, 4, 5\) without repetition is \(5! = 120\). To find the number of ways where \(1\) and \(5\) are always together, treat the pair \((1, 5)\) as a single unit. This leaves us with \(4\) units:…