If \(n(A-B)=7\) and \(n(A\cap B)=3\), what is \(n(A)\)?
Answer and explanation
Correct answer: 10
The set \(A\) is made up of two disjoint regions in the Venn diagram: the part that lies only in \(A\), namely \(A-B\), and the common part \(A\cap B\). Therefore, \(n(A)=n(A-B)+n(A\cap B)=7+3=10\). Option C is correct. The values 7 and 3 are only separate portions of \(A\), while 21 is an irrelevant product.
Frequently asked questions
What is the correct answer to this question?
10
Why is this the correct answer?
The set \(A\) is made up of two disjoint regions in the Venn diagram: the part that lies only in \(A\), namely \(A-B\), and the common part \(A\cap B\). Therefore, \(n(A)=n(A-B)+n(A\cap B)=7+3=10\). Option C is correct. The values 7 and 3 are only separate portions of \(A\), while 21 is an irrelevant product.
Which subject and chapter does this question cover?
This is a Class 12 Mathematics question. Chapter: Sets.
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