# Example 7 - Chapter 13 Class 12 Probability

Last updated at March 11, 2017 by Teachoo

Last updated at March 11, 2017 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, F : Number greater than 4 on the die E : at least one tail We need to find P(E|F) Also, E ∩ F = {(T, 5), (T, 6)} So, P(E ∩ F) = P(T, 5) + P(T, 6) So, P(E ∩ F) = P(T, 5) + P(T, 6) = 112 + 112 = 212 = 16 Now, P(E|F) = 𝑃(𝐸 ∩ 𝐹)𝑃(𝐹) = 16 34 = 16 × 43 = 𝟐𝟗 Therefore, required probability is 29

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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.