If A = {x : x ∈ N, x ≤ a} and B = {1, 2, 3, 4} are equal, what is the value of a?
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Answer and explanation
Correct answer: 4
Assuming N = {1, 2, 3, ...}, the set A contains all natural numbers from 1 through a. The set B contains exactly 1, 2, 3, and 4, so its largest element is 4. For A and B to be equal, the upper bound must be a = 4. If a were 3, an element would be missing; if a were 5, an extra element would appear.
Frequently asked questions
What is the correct answer to this question?
4
Why is this the correct answer?
Assuming N = {1, 2, 3, ...}, the set A contains all natural numbers from 1 through a. The set B contains exactly 1, 2, 3, and 4, so its largest element is 4. For A and B to be equal, the upper bound must be a = 4. If a were 3, an element would be missing; if a were 5, an extra element would appear.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: The Empty Set, Finite and Infinite Sets, Equal Sets.
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