If U = {1, 2, ..., 24}, A is the set of odd numbers in U, and B is the set of prime numbers in U, what is A ∩ B′?
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Answer and explanation
Correct answer: {1, 9, 15, 21}
A ∩ B′ consists of numbers that are odd and not prime. The odd numbers from 1 to 24 are 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, and 23. Removing the odd primes 3, 5, 7, 11, 13, 17, 19, and 23 leaves {1, 9, 15, 21}. Note that 1 is not prime, so it remains.
Frequently asked questions
What is the correct answer to this question?
{1, 9, 15, 21}
Why is this the correct answer?
A ∩ B′ consists of numbers that are odd and not prime. The odd numbers from 1 to 24 are 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, and 23. Removing the odd primes 3, 5, 7, 11, 13, 17, 19, and 23 leaves {1, 9, 15, 21}. Note that 1 is not prime, so it remains.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Complement of a Set and Its Properties.
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