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Subjects
Class 10MathematicsSetsComplement of a Set and Its PropertiesEasyLevel 20

If U = {1,2,...,22} and A = {x ∈ U : x is prime}, how many odd numbers are in A′?

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Answer and explanation

Correct answer: 4

The odd numbers from 1 through 22 are 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, and 21, making 11 odd numbers. The odd primes in this range are 3, 5, 7, 11, 13, 17, and 19. Removing these seven primes leaves 1, 9, 15, and 21 in A′, so the required number is 4. Note that 1 is not prime.

Tags

setscomplementprime numbersodd numbersfinite setsMathematicsComplement of a Set and Its PropertiesClass 10 MCQ

Frequently asked questions

What is the correct answer to this question?

4

Why is this the correct answer?

The odd numbers from 1 through 22 are 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, and 21, making 11 odd numbers. The odd primes in this range are 3, 5, 7, 11, 13, 17, and 19. Removing these seven primes leaves 1, 9, 15, and 21 in A′, so the required number is 4. Note that 1 is not prime.

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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