JEE Main2016MathematicsProbabilityActual
If A and B are any two events such that P A = 2 5 and P A ∩ B = 3 20 , then the conditional probability, P A A ′ ∪ B ′ , where A ' denotes the complement of A , is equal to :
Options
- A11 20
- B5 17
- C8 17
- D1 4
Correct answer
B. 5 17
Step-by-step solution
Given P A = 2 5 = 8 20 &   P A ∩ B = 3 20 ∴     P A ' ∪ B ' = P A ∩ B ' = 1 - P A ∩ B = 1 - 3 20 = 17 20 P A ∩ A ' ∪ B ' = P A ∩ B ' = P A - P A ∩ B = 8 20 - 3 20 = 5 20     ∴     P A A ' ∪ B ' = P A ∩ A ' ∪ B ' P A ' ∪ B ' = 5 20 17 20 = 5 17