If B = {2, 2, 4, 4, 6}, what is n(B)?
Answer and explanation
Correct answer: 3
The governing set principle is that repeated listings do not create new elements. Although five entries are written, the distinct elements of B are only 2, 4, and 6. We can rewrite the set without duplicates as B = {2, 4, 6}. Therefore its cardinality is n(B) = 3. The value 5 counts written entries, not distinct set elements, so option A is correct.
Frequently asked questions
What is the correct answer to this question?
3
Why is this the correct answer?
The governing set principle is that repeated listings do not create new elements. Although five entries are written, the distinct elements of B are only 2, 4, and 6. We can rewrite the set without duplicates as B = {2, 4, 6}. Therefore its cardinality is n(B) = 3. The value 5 counts written entries, not distinct set elements, so option A is correct.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Common Questions. Topic: General chapter practice.
