GWD11-13: Theater M has 25 rows with 27 seats in each row. How many of the seats were occupied during a certain show?

(1) During the show, there was an average of 10 unoccupied seats per row for the front 20 rows.

(2) During the show, there was an average of 20 unoccupied seats per row for the back 15 rows.

答案是E,为什么啊！

条件1能得出前20排occupied的seats是：（27-10）*20

条件2能得出后15排occupied的seats是：（27-20）*15，但不能得出后5排的occupied的seats，因为已知的条件给的是平均数，没法算出部分的具体数。

所以，两个条件加在一起也得不出整个25排的 occupied  seats ，所以选E