Disjoint subsets A and B of a universal set U, except assume that n (U) = 120, n (A) = 45, and n (B) = 50.

Then n (A′∪B) =

n (A' U B) = 75

Step-by-step explanation:

Here, given : n (U) = 120, n (A) = 45, and n (B) = 50

As we know:

n (A ' U B) = n (A) - n (A∩B) ... (1)

Here, n (A) = 45

So, n (A') = n (U) - n (A) = 120 - 45 = 75

⇒ n (A') = 75

Now, as given A and B are disjoint sets.

⇒ n (A ∩ B) = Ф

So, (A' U B) = A'

So, n (A' U B) = n (A') = 75

⇒ n (A' U B) = 75