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
- A \(\frac{2}{5}\)
- B \(\frac{1}{5}\)
- C \(\frac{3}{5}\)
- D \(\frac{1}{4}\)
Answer & Solution
Correct Answer
(A) \(\frac{2}{5}\)
Step-by-step Solution
Detailed explanation
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 \(=2 \times 4\) ! \(\therefore\) Required probability \(=\frac{2 \times 4 !}{5 !}=\frac{2 \times 4 !}{5 \times 4 !}=\frac{2}{5}\)
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