Magoosh, Hard, Assumption

lincolnseattleUID：3553649

In a freshman biochemistry class at Newton University, the teacher assigns the class only ‘A’s, ‘B’s’ or ‘C’s. The average on the semester final for the class of 2012 was five points lower than that of the class of 2011. Therefore, the percent of students who received ‘C’s was greater in 2012 than in 2011.

Which of the following, if true, suggests the conclusion above is not necessarily valid?

a. There was a greater number of students in the 2011 class than in the 2012 class.
b. The percent of students who received ‘A’s in 2011 was less than in 2012.
c. Five more students received ‘A’s in 2012 than in 2011.
d. The same number of students received ‘B’s in 2011 as in 2012.
e. The percent of students who received ‘B’s was greater in 2012 than in 2011.

Verbal里面出了一道数学题。赶上我数学又是语文老师教的。

希望能有热心G友 解答下 这题怎么做尤其是思路是什么 谢谢！！

淡蓝色的不灭之光UID：3729359

2012年的平均分比2011年的低，不一定是2012年得C的人的比例更高，也有可能是2012年得A的人的比例少了，得B的人的比例多了，导致平均分变低了。所以选e。
这也不算是数学题

淡蓝色的不灭之光UID：3729359

要想平均分变低，可以是C的比例变高了，也可以C的比例不变，是B的比例变高了