Let A and B be two sets containing 2 elements and 4 elements respectively. The number of subsets of A×B having 3 or more elements is

Now according to the given condition, the number of subsets will be
Let A = {a, b}, B = {x, y, z, w}
Total number of elements in A×B = 8
Total number of subsets in A×B = 2⁸ = 256
Number of subsets having 3 or more elements = 256 - (no. of subsets having (1 element + 2 elements + 0 elements))
= 2⁸ - (⁸C₀ + ⁸C₁ + ⁸C₂) = 256 - (1 + 8 + 28) = 256 - 37 = 219.