Which set is C = {x : x ∈ N, x is a multiple of 5 between 10 and 30}?
Answer and explanation
Correct answer: C = {15, 20, 25}
The governing idea is roster notation with a strict interval. “Between 10 and 30” means 10 < x < 30, so neither endpoint is included. The natural-number multiples of 5 in this open interval are 15, 20 and 25. Option A and option D incorrectly include one or both endpoints, while option C also includes 5, which lies outside the interval. Therefore option B is correct.
Frequently asked questions
What is the correct answer to this question?
C = {15, 20, 25}
Why is this the correct answer?
The governing idea is roster notation with a strict interval. “Between 10 and 30” means 10 < x < 30, so neither endpoint is included. The natural-number multiples of 5 in this open interval are 15, 20 and 25. Option A and option D incorrectly include one or both endpoints, while option C also includes 5, which lies outside the interval. Therefore option B is correct.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems.
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