CA Foundation · Quantitative Aptitude · Sets, Relations and Functions, Limits and Continuity
The set A = {x : x is a natural number and 3 < x ≤ 9} is written in roster form as:
The set is {4, 5, 6, 7, 8, 9}. The inequality 3 < x leaves out 3, while x ≤ 9 keeps 9, so the natural numbers from 4 up to and including 9 form the set.
- A{3, 4, 5, 6, 7, 8, 9}
- B{4, 5, 6, 7, 8}
- C{4, 5, 6, 7, 8, 9}Correct
- D{3, 4, 5, 6, 7, 8}
Explanation
The condition 3 < x excludes 3, and x ≤ 9 includes 9. So the natural numbers are 4, 5, 6, 7, 8, 9. The option {4, 5, 6, 7, 8} wrongly excludes the upper limit 9.
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