Answer:
AUB = {E1, E2, E4, E6, E7}
Step-by-step explanation:
Since we are to look for the union of the two sets, therefore we combine all the sample points that are contained in A and B without repeating any sample even if such sample occur in both sets. For example, E4 occurs in event A and B and as such will only be repeated once in the union of the two events.
AUB = {E1, E2, E4, E6, E7}
Note that the way you arrange does not matter as well.
I hope you find this solution useful?