Let A = {1, 5, 11, 12, 13} and B = {3, 6, 8, 10, 11}. What is A ∪ B?
Note
A ∪ B means all elements that are in A or in B or in both. Write each element once only. The union includes all elements or students that belong to either group. Count shared elements only once, because they are already part of both groups. The correct answer is {1, 3, 5, 6, 8, 10, 11, 12, 13}, which matches the calculation or reasoning shown.