यदि (n(A)=50), (n\(A\cap B\)=21), (n\(A\cap C\)=19) और (n\(A\cap B\cap C\)=8) है, तो केवल (A) कितने हैं?
If (n(A)=50), (n\(A\cap B\)=21), (n\(A\cap C\)=19), and (n\(A\cap B\cap C\)=8), how many are only in (A)?
Explanation opens after your attempt
B. (18)
Concept
Only (A=50-21-19+8=18). The central part is subtracted twice, so it is added once.
Why this answer is correct
The correct answer is B. (18). Only (A=50-21-19+8=18). The central part is subtracted twice, so it is added once.
Exam Tip
केवल (A=50-21-19+8=18) है। केंद्रीय भाग दो बार घटता है, इसलिए एक बार जोड़ा जाता है।
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