If U={1,2,…,18} and A is the set of primes in U, which set of multiples of 3 lies in A′?
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Answer and explanation
Correct answer: {6,9,12,15,18}
The multiples of 3 in U are {3,6,9,12,15,18}. The number 3 is prime, so it belongs to A and cannot belong to A′. Each of 6, 9, 12, 15, and 18 is composite, so all five belong to the complement of the prime-number set. Consequently, the required set is {6,9,12,15,18}, which is option A.
Frequently asked questions
What is the correct answer to this question?
{6,9,12,15,18}
Why is this the correct answer?
The multiples of 3 in U are {3,6,9,12,15,18}. The number 3 is prime, so it belongs to A and cannot belong to A′. Each of 6, 9, 12, 15, and 18 is composite, so all five belong to the complement of the prime-number set. Consequently, the required set is {6,9,12,15,18}, which is option A.
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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