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NCERT Class 12 · Ch 13 Exercise 13.1 · Q12

NCERT Class 12 Maths · Chapter 13 Probability · Exercise 13.1 Question 12

Two children are independently equally likely to be boys or girls. Find P(both girls | (i) youngest a girl, (ii) at least one girl).

💡 Concept Hints

  1. Define the events and identify which event is being conditioned on.
  2. Use P(E|F)=P(E∩F)/P(F), or separate the possible sources before applying total probability and Bayes.

✅ Step-by-Step Solution

Final Answer: (i) 1/2; (ii) 1/3.
  1. Use the equally likely ordered pairs (elder,younger): BB,BG,GB,GG.
  2. (i) Restrict to BG,GG; one of two is GG. (ii) Restrict to BG,GB,GG; one of three is GG.

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