If the probability of A to fail in an examination is and that of B is . Then, the probability that either A or B fails is

Question

Philoid · Accepted Answer

Let A be the event that student ‘A’ fails in exam and B be the event that student ‘B’ fails in exam.

Given, P(A) = 1/5 and P(B) = 3/10

We have to find P(A ∪ B)

We know that P(A ∪ B) = P(A) + P(B) – P(A ∩ B)

As P(A ∩ B) not given, so assuming its value 0

∴ P(A ∪ B) = 1/5 + 3/10 = 5/10 = 1/2

As our answer matches with option (a)

∴ Option (a) is the only correct choice.