Correct option (d)
Explanation:
A and B will agree in a certain statement if both speak truth or both tell a lie. We define following events
E1 = A and B both speak truth
⇒ P(E1) = xy
E2 = A and B both tell a lie
⇒ P (E2 ) = (1 – x ) (1 – y)
E = A and B agree in a certain statement
Clearly, P(E/ E1) = 1 and P(E/E2) = 1
The required probability is P(E1/ E). Using Baye’s theorem