Ex 14.2

Chapter 14 Class 11 Probability
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### Transcript

Ex 14.2, 18 In Class XI of a school 40% of the students study Mathematics and 30% study Biology. 10% of the class study both Mathematics and Biology. If a student is selected at random from the class, find the probability that he will be studying Mathematics or Biology. Let B be the event of student studying biology. & M be the event of student studying maths Hence Probability student study maths = 40% P(M) = 40 % = 40﷮100﷯ = 0.4 Probability student study biology = 30% P(B) = 30% = 30﷮100﷯ = 0.3 Given Students who study both maths and biology are 10% Hence P (M ∩ B) = 10% = 10﷮100﷯ = 0.10 We need to find probability student studying either math or biology i.e. P(M ∪ B) We know that P(M ∪ B) = P(M) + P(B) – P(M∩B) Putting values = 0.4 + 0.3 – 0.10 = 0.7 – 0.10 = 0.6 Hence, probability student studying either math or biology = 0.6

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#### Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.