Example 8 - Chapter 13 Class 12 Probability
Last updated at Dec. 8, 2016 by Teachoo
Transcript
Example 8 An urn contains 10 black and 5 white balls. Two balls are drawn from the urn one after the other without replacement. What is the probability that both drawn balls are black? We need to find probability that both balls drawn out are black Let the events be E : First ball drawn is black F : Second ball drawn is black Probability both balls drawn are black = Probability first ball drawn is black × Probability second ball is black if first is black P(E ∩ F) = P(E) P(F|E) P(E) is Probability first ball drawn is black There are 10 blacks balls out of 15 So, P(E) = 1015 = 23 P(F|E) is the Probability of F after E has happened i.e. probability of second ball drawn black if first ball was black If first ball drawn was black, we are left with 9 black, 5 white balls P(F|E) = 𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 𝐵𝑙𝑎𝑐𝑘 𝑏𝑎𝑙𝑙𝑟𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 𝑏𝑎𝑙𝑙𝑠 = 914 Now, P(E ∩ F) = P(E) P(F|E) . = 23 × 914 = 𝟑𝟕
Examples
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Example 3
Example 4
Example 5
Example 6 Important
Example 7 Important
Example 8 You are here
Example 9
Example 10
Example 11 Important
Example 12
Example 13
Example 14
Example 15
Example 16
Example 17 Important
Example 18 Important
Example 19
Example 20 Important
Example 21 Important
Example 22
Example 23
Example 24
Example 25 Important
Example 26 Important
Example 27 Important
Example 28 Important
Example 29 Important
Example 30
Example 31 Important
Example 32 Important
Example 33
Example 34
Example 35 Important
Example 36 Important
Example 37
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 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.