Let A = {1, 2, 3, 4} and B = {x : x is a positive natural number and x² < 20}. Which conclusion is correct?
Answer and explanation
Correct answer: A = B
To determine B, test positive natural numbers against x² < 20. We get 1² = 1, 2² = 4, 3² = 9, and 4² = 16, all below 20. However, 5² = 25, so 5 and every larger positive natural number are excluded. Hence B = {1, 2, 3, 4}, exactly the same set as A. Therefore A = B, making option A correct; B is neither empty nor infinite.
Frequently asked questions
What is the correct answer to this question?
A = B
Why is this the correct answer?
To determine B, test positive natural numbers against x² < 20. We get 1² = 1, 2² = 4, 3² = 9, and 4² = 16, all below 20. However, 5² = 25, so 5 and every larger positive natural number are excluded. Hence B = {1, 2, 3, 4}, exactly the same set as A. Therefore A = B, making option A correct; B is neither empty nor infinite.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Sets and their representations.
