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CUET · MATHS · PYQ PAPER 2025

There are 50 telephone lines in an exchange. The probability that any one of them will be busy is 0.1, then the probability that all the lines are busy?

  1. A \(\frac{e^{-5} \times 5^{50}}{5!}\)
  2. B \(\frac{e^{-5} \times 5^{50}}{50!}\)
  3. C \(\frac{e^{-50} \times 50^{50}}{50!}\)
  4. D \(\frac{e^{-50} \times 50^5}{50!}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{e^{-5} \times 5^{50}}{50!}\)

Step-by-step Solution

Detailed explanation

\( n = 50 \) \( p = 0.1 \) \( \lambda = n p = 50 \times 0.1 = 5 \) \( P(X=50) = \frac{e^{-\lambda} \lambda^{50}}{50!} = \frac{e^{-5} 5^{50}}{50!} \)