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CUET · MATHS · PYQ PAPER 2025

An urn contains 5 red and 5 black balls. A ball is drawn at random, its color is noted and is returned to the urn.
Moreover, 2 additional balls of the same color are put in the urn and then a ball is drawn at random.
The probability that the second drawn ball is red, is :

  1. A \(\frac{5}{12}\)
  2. B \(\frac{1}{2}\)
  3. C \(\frac{1}{3}\)
  4. D \(\frac{1}{4}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{1}{2}\)

Step-by-step Solution

Detailed explanation

\(P(\text{2nd R}) = P(\text{1st R}) \cdot P(\text{2nd R | 1st R}) + P(\text{1st B}) \cdot P(\text{2nd R | 1st B})\) \(P(\text{2nd R}) = \frac{5}{10} \cdot \frac{5+2}{10+2} + \frac{5}{10} \cdot \frac{5}{10+2}\)…