# Ex 13.5, 15 (MCQ) - Chapter 13 Class 12 Probability (Term 2)

Last updated at Aug. 11, 2021 by Teachoo

Last updated at Aug. 11, 2021 by Teachoo

Transcript

Ex 13.5, 15 The probability that a student is not a swimmer is 1/5 . Then the probability that out of five students, four are swimmers is (A) 5C4 (4/5)^4 1/5 (B) (4/5)^4 1/5 (C) 5C1 1/5 (4/5)^4 (D) None of theseIf 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 number of swimmers Picking a student is a Bernoulli trial So, X has binomial distribution P(X = x) = nCx 𝒒^(𝒏−𝒙) 𝒑^𝒙 Here, n = number of students = 5 Given probability that student is not a swimmer is 1/5 So, q = 1/5 ∴ p = 1 – q = 1 – 1/5 = 4/5 Hence, P(X = x) = 5Cx (𝟒/𝟓)^𝒙 (𝟏/𝟓)^(𝟓 − 𝒙) We need to find the Probability of that out of five students, four are swimmers i.e. P(X = 4) P(X = 4) = 5C4 (4/5)^4 (1/5)^(5 − 4) = 5C4 (𝟒/𝟓)^𝟒 𝟏/𝟓 = 5C1 𝟏/𝟓 (𝟒/𝟓)^𝟒 Hence, option (A) & (C) both are correct

Ex 13.5

Ex 13.5, 1
Deleted for CBSE Board 2022 Exams

Ex 13.5, 2 Deleted for CBSE Board 2022 Exams

Ex 13.5, 3 Important Deleted for CBSE Board 2022 Exams

Ex 13.5, 4 Important Deleted for CBSE Board 2022 Exams

Ex 13.5, 5 Deleted for CBSE Board 2022 Exams

Ex 13.5, 6 Important Deleted for CBSE Board 2022 Exams

Ex 13.5, 7 Important Deleted for CBSE Board 2022 Exams

Ex 13.5, 8 Deleted for CBSE Board 2022 Exams

Ex 13.5, 9 Deleted for CBSE Board 2022 Exams

Ex 13.5, 10 Important Deleted for CBSE Board 2022 Exams

Ex 13.5, 11 Deleted for CBSE Board 2022 Exams

Ex 13.5, 12 Deleted for CBSE Board 2022 Exams

Ex 13.5, 13 Important Deleted for CBSE Board 2022 Exams

Ex 13.5, 14 (MCQ) Important Deleted for CBSE Board 2022 Exams

Ex 13.5, 15 (MCQ) Important Deleted for CBSE Board 2022 Exams You are here

Chapter 13 Class 12 Probability (Term 2)

Serial order wise

About the Author

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.