What is F={x∈N: x is an odd composite number less than 25}?
Answer and explanation
Correct answer: F={9,15,21}
The governing concept is classifying numbers using parity and primality. Odd composite numbers below 25 are 9,15,21: each is odd and has factors other than 1 and itself. The listed odd primes belong to option B’s distractor set, 1 is neither prime nor composite, and 25 is excluded by the strict condition x<25. Therefore option A is correct.
Frequently asked questions
What is the correct answer to this question?
F={9,15,21}
Why is this the correct answer?
The governing concept is classifying numbers using parity and primality. Odd composite numbers below 25 are 9,15,21: each is odd and has factors other than 1 and itself. The listed odd primes belong to option B’s distractor set, 1 is neither prime nor composite, and 25 is excluded by the strict condition x<25. Therefore option A is correct.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems.
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