求助GWD4-Q2

woklovepp

怎么GWD31套的题目和讨论稿中的题目不一样呢？

Q2：What is the ratio of the average (arithmetic mean) height of students in class X to the average height of students in class Y?

(1)     The average height of the students in class X is 120 centimeters.

(2)   The average height of the students in class X and class Y combined is 126 centimeters.

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

Answer: e

这题c为什么不对，已知X班的平均身高，XY班combine的平均身高，应该可以推出Y班平均身高阿

heatostrich

不知道X,Y班上人数的比例是多少啊。人数的比例不同，算出来的Y的平均身高是不一样的。比如，比例是1:1,那么Y的平均身高是132CM,如果是1：2，Y的平均身高应该是129CM...所以E