If \(U=\{1,2,3,\ldots,20\}\), \(A=\{x:x\text{ is prime}\}\), and \(B=\{x:x\text{ is odd}\}\), what is \(A^c\cap B\)?
Answer and explanation
Correct answer: \(\{1,9,15\}\)
The set \(B\) consists of all odd numbers from 1 to 20. The odd prime numbers in this range are 3, 5, 7, 11, 13, 17, and 19. Removing these from B leaves the odd, non-prime numbers \(\{1,9,15\}\). Note that 1 is not prime, because a prime number must have exactly two distinct positive divisors.
Frequently asked questions
What is the correct answer to this question?
\(\{1,9,15\}\)
Why is this the correct answer?
The set \(B\) consists of all odd numbers from 1 to 20. The odd prime numbers in this range are 3, 5, 7, 11, 13, 17, and 19. Removing these from B leaves the odd, non-prime numbers \(\{1,9,15\}\). Note that 1 is not prime, because a prime number must have exactly two distinct positive divisors.
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.