GWD-29

Q9:

A total of 100 customers purchased books at a certain bookstore last week.  If these customers purchased a total of 200 books, how many of the customers purchased only 1 book each?

(1)   None of the customers purchased more than 3 books.（为什么不考虑3本书的情况，只说不多于，没说不等于）

(2)   20 of the customers purchased only 2 books each.

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: C

Q25:这道题我不太明白应该如何向乘，可以帮我列个式子吗？

An office supply store received a shipment of boxes of pencils.  How many pencils were in the shipment altogether?  (1 gross = 12 dozen)

(1)     The number of boxes of pencils in the shipment was 6 gross.

(2)     There were 3 dozen pencils in each box of pencils in the shipment.

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: C

Q25:

1. 只知到 boxes, 不知道每個box裡有多少pencils

2. 只知到每個box裡有多少pencils 不知道總共有幾個boxes

C --- pencils= 6*12*3 (dozen)

Q9: 就是因为考虑了3本书的情况才会有解，（1）说每人买1本2本或3本，（2）说买2本的20人，综合在一起说明其余80人共买了160本书，但每人买不是1本就是3本。因此有x+y=80, x+3y=160能够唯一确定x。

Q9 :列式子会比较清楚

   设买一本的人为a   买三本的人为 b

   a+b = 80

   a+3b = 160

   可以求出只买一本的人 

(1 gross = 12 dozen)

这个干吗用的？知道A不就可以求出来了吗？6*12铅笔数