[Value = 6 points]
X, Y, and Z are pairwise disjoint sets of people. The average age of people in X is 37. The average age of people in Y is 23. The average age of people in Z is 41. The average age of people in X ∪ Y is 29. The average age of people in X ∪ Z is 39.5. The average age of people in Y ∪ Z is 33.
What is the average age of people in X ∪ Y ∪ Z?
