यदि (n(A)=42), (n\(A\cup B\)=69), और (n\(A\cap B\)=18), तो (n(B)) क्या है?
If (n(A)=42), (n\(A\cup B\)=69), and (n\(A\cap B\)=18), what is (n(B))?
Explanation opens after your attempt
B. (45)
Concept
From (69=42+n(B)-18), we get (n(B)=45). Isolate the unknown in the union formula.
Why this answer is correct
The correct answer is B. (45). From (69=42+n(B)-18), we get (n(B)=45). Isolate the unknown in the union formula.
Exam Tip
सूत्र (69=42+n(B)-18) से (n(B)=45) मिलता है। संघ के सूत्र में अज्ञात को अलग करें।
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