\(यदि (U={1,2,\ldots,21}), (A={x:x\) 3 से विभाज्य है}), तो (A') में कितने अवयव विषम हैं?
\(If (U={1,2,\ldots,21}), (A={x:x\) is divisible by 3}), how many odd elements are in (A')?
Explanation opens after your attempt
Correct Answer
B. (7)
Concept
From (1) to (21), there are (11) odd numbers, and (3,9,15,21) are divisible by (3). So odd elements in (A') are (11-4=7).
Why this answer is correct
The correct answer is B. (7). From (1) to (21), there are (11) odd numbers, and (3,9,15,21) are divisible by (3). So odd elements in (A') are (11-4=7).
Exam Tip
(1) से (21) तक (11) विषम संख्याएँ हैं और उनमें (3,9,15,21) (3) से विभाज्य हैं। इसलिए (A') में विषम अवयव (11-4=7) हैं।
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