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Last updated at Feb. 15, 2020 by Teachoo

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Ex 13.5, 13 It is known that 10% of certain articles manufactured are defective. What is the probability that in a random sample of 12 such articles, 9 are defective? In each of the following, choose the correct answer:vIf a trial is Bernoulli, then There is finite number of trials They are independent Trial has 2 outcomes i.e. Probability success = P then Probability failure = q = 1 – P (4) Probability of success (p) is same for all trials Let X : be the number of defective articles Picking articles is a Bernoulli trial So, X has binomial distribution P(X = x) = nCx 𝒒^(𝒏−𝒙) 𝒑^𝒙 Here, n = number of articles = 12 p = Probability of getting defective articles = 10% = 10/100 = 1/10 q = 1 – p = 1 – 1/10 = 9/10 Hence, P(X = x) = 12Cx (𝟏/𝟏𝟎)^𝒙 (𝟗/𝟏𝟎)^(𝟏𝟐−𝒙) Picking articles is a Bernoulli trial So, X has binomial distribution P(X = x) = nCx 𝒒^(𝒏−𝒙) 𝒑^𝒙 Here, n = number of articles = 12 p = Probability of getting defective articles = 10% = 10/100 = 1/10 q = 1 – p = 1 – 1/10 = 9/10 Hence, P(X = x) = 12Cx (𝟏/𝟏𝟎)^𝒙 (𝟗/𝟏𝟎)^(𝟏𝟐−𝒙) We need to find Probability of getting 9 defective articles out of 12 i.e. P(X = 9) P(X = 9) = 12C9 (1/10)^9 (9/10)^(12 − 9) = (12 !)/((12 − 9) ! 9 !) (1/10)^9 (9/10)^3 = (12 × 11 × 10 × 9 !)/(3 ! 9 !) \ ×1/〖10〗^9 (9/10)^3 = (12 × 11 × 10)/(3 × 2 × 1) × 1/〖10〗^9 (9/10)^3= (2 × 11)/〖10〗^8 9^3/〖10〗^3 = 22 (𝟗^𝟑/〖𝟏𝟎〗^𝟏𝟏 )

Ex 13.5

Ex 13.5, 1
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Ex 13.5, 2 Deleted for CBSE Board 2021 Exams only

Ex 13.5, 3 Important Deleted for CBSE Board 2021 Exams only

Ex 13.5, 4 Important Deleted for CBSE Board 2021 Exams only

Ex 13.5, 5 Deleted for CBSE Board 2021 Exams only

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Ex 13.5, 9 Deleted for CBSE Board 2021 Exams only

Ex 13.5, 10 Important Deleted for CBSE Board 2021 Exams only

Ex 13.5, 11 Deleted for CBSE Board 2021 Exams only

Ex 13.5, 12 Deleted for CBSE Board 2021 Exams only

Ex 13.5, 13 Important Deleted for CBSE Board 2021 Exams only You are here

Ex 13.5, 14 Important Deleted for CBSE Board 2021 Exams only

Ex 13.5, 15 Important Deleted for CBSE Board 2021 Exams only

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 10 years. He provides courses for Maths and Science at Teachoo.