If A is a subset of B and B is a subset of C, then the cardinality of A ∪ B ∪ C is equal to:

Question

Question

This question was previously asked in

NIMCET 2020 Official Paper

Answer 1

Concept:

The cardinality of a set A is the measure of the "number of elements" of the set. It is denoted by n(A).
For example, a set containing 3 elements has a cardinality of 3.
If A ⊂ B, then A ∪ B = B.

Calculations:

Since, A ⊂ B and B ⊂ C, therefore A ∪ B ∪ C = C.

⇒ n(A ∪ B ∪ C) = n(C).

∴ The cardinality (number of elements) of A ∪ B ∪ C = cardinality (number of elements) of C.