JEE Main2014MathematicsProbabilityActual
Let A and B be two events such that P A ∪ B ¯ = 1 6 , P A ∩ B = 1 4 and P A ¯ = 1 4 , where A ¯ stands for the complement of the event A . Then the events A and B are
Options
- AIndependent but not equally likely.
- BIndependent and equally likely.
- CMutually exclusive and independent.
- DEqually likely but not independent.
Correct answer
A. Independent but not equally likely.
Step-by-step solution
P A ∪ B ¯ = 1 6 ∴     P A ∪ B = 5 6 P A ∩ B = 1 4 P A ¯ = 1 4 ∴     P A = 3 4 ∴     P A ∪ B = P A + P B - P A ∩ B ∴     5 6 = 3 4 + P B - 1 4 ∴     P B = 1 3 ∴     P A · P B = 1 3 × 3 4 = 1 4 = P A ∩ B Therefore, A and B are independent and since P A ≠ P B they are not equally likely.