Let R = {x | x ∈ N, x is a multiple of 3 and x ≤ 100} and S = {x | x ∈ N, x is a multiple of 5 and x < 100}. What is the number of elements in (R ∩ S) × (S ∩ R)?
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Correct answer: A. 36
Explanation
R ∩ S = multiples of 15 below 100 = {15, 30, 45, 60, 75, 90}, 6 elements. The Cartesian product has 6 × 6 = 36 elements.More Discrete Structures and Optimization questions
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