CUET · MATHS · PYQ PAPER 2025
A couple has 3 children each child is equally likely to be a boy or a girl. The probability that the eldest child is a girl glven that they have atleast one boy is :
- A \(\frac{1}{2}\)
- B \(\frac{3}{7}\)
- C \(\frac{4}{7}\)
- D \(\frac{3}{8}\)
Answer & Solution
Correct Answer
(B) \(\frac{3}{7}\)
Step-by-step Solution
Detailed explanation
\(S = \{BBB, BBG, BGB, GBB, BGG, GBG, GGB, GGG\}\) \(N(S) = 8\) \(A = \text{eldest child is a girl} = \{GBB, GBG, GGB, GGG\}\) \(B = \text{at least one boy} = \{BBB, BBG, BGB, GBB, BGG, GBG, GGB\}\) \(A \cap B = \{GBB, GBG, GGB\}\) \(P(A|B) = \frac{N(A \cap B)}{N(B)}\)…
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