If A is a subset of B, n(A) = 28, and n(B) = 64, how many elements are in the region B − A of the Venn diagram?
Advertisement
Answer and explanation
Correct answer: 36
Because A ⊆ B, every element of A lies inside B. The difference B − A therefore contains the elements that belong to B but not to A. For finite sets, n(B − A) = n(B) − n(A) = 64 − 28 = 36. Thus option A is correct. The values 28 and 64 refer to A and B themselves, while 92 incorrectly adds them.
Frequently asked questions
What is the correct answer to this question?
36
Why is this the correct answer?
Because A ⊆ B, every element of A lies inside B. The difference B − A therefore contains the elements that belong to B but not to A. For finite sets, n(B − A) = n(B) − n(A) = 64 − 28 = 36. Thus option A is correct. The values 28 and 64 refer to A and B themselves, while 92 incorrectly adds them.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Venn Diagrams.
Advertisement