Q11:
The total cost of an office dinner was shared equally by k of the n employees who
attended the dinner. What was the total cost of the dinner?
(1) Each of the k employees who shared the cost of the dinner paid $19.
(2) If the total cost of the dinner had been shared equally by k + 1 of the n
employees who attended the dinner, each of the k + 1 employees would have
paid $18.
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.

不明白哦,那个K不是一个以经确定的数吗？为什么先C哦

Ｋ是指n个人里头的Ｋ个人．

条件一，只知道Ｋ个人每个分摊$19, total cost=19K,不知道具体K的值，不充分；

条件二，total cost =(k+1)18,还是不知道Ｋ的具体数值，不充分；

(1)+(2) 解方程组，能解出Ｋ的具体值从而得出total cost，充分．

所以选Ｃ．