Q4 of 86 Page 24

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?

Given-


n(S) = 21, n(T) = 32, and n(S ∩ T) = 11


We know that-


n(S ∪ T) = n(S)+ n(T) - n(S ∩ T)


= 21+32 - 11


= 53 - 11


= 42


∴ n(S ∪ T) = 42


Thus, the no. of elements in n(S ∪ T) is 42.


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