148. If the variables, X, Y, and Z take on only the values 10,20,30,40,50,60,or 70 with frequencies indicated
by the shaded regions above, for which of the frequency distributions is the mean equal to the median?
a. X only
b. Y only
c. Z only
d. X and Y
e. X and Z
提问:题目的意思是说中位数和平均数相同吗?这样的话Y为何不对?
图在这里,之前有人问过了,但是没有合理的解释。。。
http://forum.Topway.com/GMAT_Math/thread-446843-1-1.html?postid=13966055&searchmode=TopicContent&searchtext=frequency%20distributio、