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NTA Abhyas 2020
Exam
NTA Abhyas
Year
2020
Subject
Mathematics
Chapter
Sets and Relations

NTA Abhyas 2020 · Mathematics · Sets and Relations

For two sets A and B , if n (A) = 20, n (B) = 18 and n(A B) = 5 ,...

For two sets AandBA and B, if n(A)=20,n(B)=18andn(A∩B)=n \left(A\right) = 20, n \left(B\right) = 18 and n\left(A \cap B\right) =5,thenn(A−B), then n\left(A - B\right) is equal to

Options

  1. A1313
  2. B1212
  3. C1515
  4. D1818

Correct answer

C. 1515

Step-by-step solution

n(A−B)=n(A∪B)−n \left(A - B\right) = n \left(A \cup B\right) -n\left(B\right) =n(A)n\left(A\right)- n(A∩B)<br/>n\left(A \cap B\right)<br />= 20 - 5<br/><br />= 15
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