If A = {x ∈ N : x is a multiple of 4 and x ≤ 20}, what is A equal to?
Answer and explanation
Correct answer: {4, 8, 12, 16, 20}
The positive natural-number multiples of 4 are 4, 8, 12, 16, 20, 24, and so on. The condition x ≤ 20 excludes every multiple after 20, while 20 itself is included because equality is allowed. Therefore the complete set is {4, 8, 12, 16, 20}. It is finite because the upper bound leaves only five possible multiples. Zero is not included under the stated positive-natural-number convention.
Frequently asked questions
What is the correct answer to this question?
{4, 8, 12, 16, 20}
Why is this the correct answer?
The positive natural-number multiples of 4 are 4, 8, 12, 16, 20, 24, and so on. The condition x ≤ 20 excludes every multiple after 20, while 20 itself is included because equality is allowed. Therefore the complete set is {4, 8, 12, 16, 20}. It is finite because the upper bound leaves only five possible multiples. Zero is not included under the stated positive-natural-number convention.
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.
