Answer: 3500 (choice C)
Step-by-step explanation:
The set of numbers is {3000, 4000, 5000, 2000} in which we can think of as {3,4,5,2} but each number represents thousands. This sorts to {2,3,4,5}
The average of that is (2+3+4+5)/4 = 14/4 = 3.5 which represents 3.5 thousand or 3.5*1000 = 3500
Therefore, the average of the original set is 3500