If A = {2, 4, 6}, what is the value of n(A)?
Answer and explanation
Correct answer: 3
The governing concept is cardinality, or the number of distinct elements in a set. The notation n(A) denotes the cardinality of A, not the value of its largest element and not the sum of its elements. In A = {2, 4, 6}, the distinct members are 2, 4, and 6, so there are exactly three elements. Therefore n(A) = 3 and option B is correct. Option A counts too few elements, option C counts one extra element, and option D confuses the member 6 with the number of members. Repetition would not increase cardinality, but no repeated element occurs here.
Frequently asked questions
What is the correct answer to this question?
3
Why is this the correct answer?
The governing concept is cardinality, or the number of distinct elements in a set. The notation n(A) denotes the cardinality of A, not the value of its largest element and not the sum of its elements. In A = {2, 4, 6}, the distinct members are 2, 4, and 6, so there are exactly three elements. Therefore n(A) = 3 and option B is correct. Option A counts too few elements, option C counts one extra element, and option D confuses the member 6 with the number of members. Repetition would not increase cardinality, but no repeated element occurs here.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Common Questions. Topic: General chapter practice.
