# Example 7 - Chapter 13 Class 12 Probability (Important Question)

Last updated at Feb. 15, 2020 by Teachoo

Last updated at Feb. 15, 2020 by Teachoo

Transcript

Example 7 Consider the experiment of tossing a coin. If the coin shows head, toss it again but if it shows tail, then throw a die. Find the conditional probability of the event that ‘the die shows a number greater than 4’ given that ‘there is at least one tail’.A coin is tossed If the coin shows head, it is tossed again. If it shows tail, then a die is thrown. Hence different value of probabilities are We need to find the probability that the die shows a number greater than 4, given that there is at least one tail. Now, E : at least one tail F : Number greater than 4 on the die We need to find P(E|F) Also, E ∩ F = {(T, 5), (T, 6)} E = { (T, 5), (T, 6) } P(E) = P(T, 5), P(T, 6) = 1/12 + 1/12 = 2/12 = 1/6 F = { (H, T), (T, 1), (T, 2), (T, 3), (T, 4), (T, 5), (T, 6) } P(F) = P(H,T) + P(T,1) + P(T,2) + P(T,3) + P(T,4) + P(T,5) + P(T,6) = 1/4 + 1/12 + 1/12 +1/12 +1/12 +1/12 + 1/12 + 1/12 = 1/4 + 6/12 = 1/4 + 1/2 = 3/4 So, P(E ∩ F) = P(T, 5) + P(T, 6) = 1/12 + 1/12 = 2/12 = 1/6 Now, P(E|F) = (𝑃(𝐸 ∩ 𝐹))/(𝑃(𝐹)) = (1/6)/(3/4) = 1/6 × 4/3 = 𝟐/𝟗 Therefore, required probability is 2/9

Chapter 13 Class 12 Probability

Example 7
Important
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Example 6

Ex 13.1, 10 Important

Ex 13.1, 12 Important

Example 11 Important

Ex 13.2, 7 Important

Ex 13.2, 11 Important

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Example 17 Important

Example 18 Important

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Example 21 Important

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Example 25 Important

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Example 27

Example 28 Important

Example 29 Important

Ex 13.4, 3 Important

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Ex 13.4, 15

Example 31 Important

Example 32 Important

Ex 13.5, 4 Important

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Example 35 Important

Example 36 Important

Misc 6 Important

Misc 9 Important

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Misc 13 Important

Misc 16 Important

Class 12

Important Questions 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

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.