If X and Y are two sets such that X ∪ Y has 70 elements, X has 38 elements and Y has 42 elements, how many elements does X ∩ Y have?
If X and Y are two sets such that X ∪ Y has 70 elements, X has 38 elements and Y has 42 elements, how many elements does X ∩ Y have? Correct Answer 10
Concept:
n(X ∪ Y) = n(X) + n(Y) – n(X ∩ Y)
Calculation:
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Given: n (X ∪ Y) = 70, n (X) = 38, n (Y) = 42
By using the formula,
n(X ∪ Y) = n(X) + n(Y) – n(X ∩ Y)
⇒ n(X ∩ Y) = n (X) + n (Y) – n (X ∪ Y)
⇒ n(X ∪ Y) = 38 + 42 – 70
∴ n(X ∪ Y) = 10
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Feb 20, 2025