Let A = {x : x is a multiple of 3} and B = {x : x is a multiple of 5}. Then A ∩ B is given by
Answer & explanation
Correct answer: option 3
Since x ∈ A ∩ B ⇔ x ∈ A and x ∈ B ⇔ x is a multiple of 3 and x is a multiple of 5 ⇔ x is a multiple of 15.
Hence A ∩ B = {x | x is a multiple of 15} = {15, 30, 45, …}.
Hence (3) is the correct answer.