# Ex 13.1, 12

Last updated at May 29, 2018 by Teachoo

Last updated at May 29, 2018 by Teachoo

Transcript

Ex 13.1, 12 Assume that each born child is equally likely to be a boy or a girl. If a family has two children, what is the conditional probability that both are girls given that (i) the youngest is a girl A family has 2 children Let girls be denoted by ‘g’ & boys be denoted by ‘b’ S = {(g, g), (g, b), (b, g), (b, b)} We need to find the Probability that both the children are girls, given that the youngest is a girl. Let F : youngest child in a girl E : both the children are girls We need to find P(E|F) Also, E ∩ F = {(g, g)} So, P(E ∩ F ) = 14 Now, P(E|F) = 𝑃(𝐸 ∩ 𝐹)𝑃(𝐹) = 14 12 = 14 × 21 = 𝟏𝟐 Ex 13.1, 12 Assume that each born child is equally likely to be a boy or a girl. If a family has two children, what is the conditional probability that both are girls given that (ii) at least one is a girl? S = {(g, g), (g, b), (b, g), (b, b)} We need to find the probability that the children are girls, given that at least one is a girl. F : at least one child is a girl E : both the children are girls Also, E ∩ F = {(g, g)} So, P(E ∩ F ) = 14 Now, P(E|F) = 𝑃(𝐸 ∩ 𝐹)𝑃(𝐹) = 14 34 = 14 × 43 = 13 ∴ P(E|F) = 𝟏𝟑

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Class 12

Important Question for exams Class 12

- Chapter 1 Class 12 Relation and Functions
- Chapter 2 Class 12 Inverse Trigonometric Functions
- Chapter 3 Class 12 Matrices
- Chapter 4 Class 12 Determinants
- Chapter 5 Class 12 Continuity and Differentiability
- Chapter 6 Class 12 Application of Derivatives
- Chapter 7 Class 12 Integrals
- Chapter 8 Class 12 Application of Integrals
- Chapter 9 Class 12 Differential Equations
- Chapter 10 Class 12 Vector Algebra
- Chapter 11 Class 12 Three Dimensional Geometry
- Chapter 12 Class 12 Linear Programming
- Chapter 13 Class 12 Probability

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.