Question 4 - Number of elements in Set Formula - Chapter 1 Class 11 Sets

Last updated at July 20, 2026 by

Ex 1.6, 4 - If S has 21 elements, T 32 elements, find S U T

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Question 4 If S and T are two sets such that S has 21 elements, T has 32 elements, and S ∩ T has 11 elements, how many elements does S ∪ T have? n(S) = 21, n(T) = 32, n(S ∩ T) = 11 We know that: n (S ∪ T) = n (S) + n (T) – n (S ∩ T) ∴ n (S ∪ T) = 21 + 32 – 11 = 42 Thus, the set (S ∪ T) has 42 elements.

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