For which of the following is the median and mean the same?
Answer: A
The mean and median are the same for a data set that is symmetrically distributed.
The set {1, 2, 3, 4, 5} is an arithmetic progression, which is a symmetric distribution.
Mean = (1+2+3+4+5)/5 = 15/5 = 3.
Median = The middle value, which is 3.
All other sets are skewed.