If A={x:x is prime and 10<x<30}, which is its roster form?
Answer and explanation
Correct answer: A={11,13,17,19,23,29}
The governing concept is converting a set-builder description into roster form. The strict inequalities require prime numbers greater than 10 and less than 30. Testing the primes in that interval gives 11, 13, 17, 19, 23, and 29. Number 21 is composite, 31 is outside the interval, and 10 and 30 are excluded by strict inequalities. Therefore option A is correct.
Frequently asked questions
What is the correct answer to this question?
A={11,13,17,19,23,29}
Why is this the correct answer?
The governing concept is converting a set-builder description into roster form. The strict inequalities require prime numbers greater than 10 and less than 30. Testing the primes in that interval gives 11, 13, 17, 19, 23, and 29. Number 21 is composite, 31 is outside the interval, and 10 and 30 are excluded by strict inequalities. Therefore option A is correct.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems. Topic: Exponents.
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