NTA Abhyas JEE Main2020MathematicsProbabilityPractice
Shubham has 75 % chance of attending the annual meet. Shikha has a 90 % chance if Shubham also attends otherwise she has a 40 % chance of attending the meet. If I go to the annual meet and see Shikha there, then the probability that Shubham is also there, is
Options
- A27 31
- B19 30
- C1 5
- D9 10
Correct answer
A. 27 31
Step-by-step solution
A = Shubham attends annual meet, P A = 3 4 B = Shikha attends annual meet P B A = 9 10 , P B A - = 4 10 = 2 5 P A B = P A ⋅ P B A P A ⋅ P B A + P A ¯ P B A - = 3 4 × 9 10 3 4 × 9 10 + 1 4 × 4 10 = 27 31