Q17:

The number of defects in the first five cars to come through a new production line are 9, 7, 10, 4, and 6, respectively. If the sixth car through the production line has either 3, 7, or 12 defects, for which of theses values does the mean number of defects per car for the first six cars equal the median?

I. 3

II. 7

III. 12

A. I only

B. II only

C. III only

D. I and III only

题目都没读懂，大家帮帮忙

E. I, II, and III

选哪个数,使的6个缺陷的平均数和中数相同

3和12 选D