Subscribe to our Youtube Channel - https://you.tube/teachoo
Example 21 - Chapter 13 Class 12 Probability
Last updated at Feb. 15, 2020 by Teachoo
Transcript
Example 21 A man is known to speak truth 3 out of 4 times. He throws a die and reports that it is a six. Find the probability that it is actually a six.Let S1 : man speaks the truth S2 : man lies E : six on the die We need to find the Probability that it is actually a six, if the man reports that it a six i.e. P(S1|E) P(S1|E) = (๐(๐_1 ).๐(๐ธ|๐_1))/(๐(๐_1 ).๐(๐ธ|๐_1)+๐(๐_2 ).๐(๐ธ|๐_2)) P(S1) = Probability that man speaks truth = ๐/๐ P(E|S1) = Probability that six appears on the die, if the man speaks the truth = ๐/๐ P(S2) = Probability man lies = 1 โ P(E) = 1 โ 3/4 = ๐/๐ P(E|S2) = Probability that six appears on the die, if the man lies = P(6 does not appear) = 1 โ 1/6 = ๐/๐ Putting value in formula, P(S1|E) = (๐(๐_1 ).๐(๐ธ|๐_1))/(๐(๐_1 ).๐(๐ธ|๐_1)+๐(๐_2 ).๐(๐ธ|๐_2)) = (3/4 ร 1/6)/( 3/4 ร 1/6 + 1/4 ร 5/6 ) = (1/4 ร 1/6 ร 3)/( 1/4 ร 1/6 [3 + 5] ) = 3/8 Therefore, required probability is ๐/๐
Examples
Example 1
Example 2
Example 3
Example 4
Example 5 Important
Example 6
Example 7 Important
Example 8
Example 9 Important
Example 10
Example 11 Important
Example 12 Important
Example 13 Important
Example 14 Important
Example 15 Important
Example 16
Example 17 Important
Example 18 Important
Example 19 Important
Example 20 Important
Example 21 Important You are here
Example 22
Example 23
Example 24 Important
Example 25 Important
Example 26 Important
Example 27 Not in Syllabus - CBSE Exams 2021
Example 28 Important Not in Syllabus - CBSE Exams 2021
Example 29 Important Not in Syllabus - CBSE Exams 2021
Example 30 Important Not in Syllabus - CBSE Exams 2021
Example 31 Important Not in Syllabus - CBSE Exams 2021
Example 32 Important Not in Syllabus - CBSE Exams 2021
Example 33 Important
Example 34 Important Not in Syllabus - CBSE Exams 2021
Example 35 Important
Example 36 Important
Example 37 Important
Chapter 13 Class 12 Probability
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 9 years. He provides courses for Maths and Science at Teachoo.