数学prep题

weiqite

请问：

Mata bought several pencils, if each pencil was either 23 cent pencil or 21 cent pencil, how many 23 cent pencils did Mata buy?

(I) Mata bought a total of 6 pencils.

(II) The total value of the pencils Mata bought was 130.

答案：Statement (II) alone is sufficient, but statement (I) alone is not sufficient.

为什么不是Both together are sufficient, but neither statement alone is not sufficient?我的考虑是：23X+21Y=130，并不可能解答出来23元的是几支铅笔的亚？请问是否我的考虑有错误？谢谢！

小小鱼儿04

因为不需要I，II单独就可以得出结论来。23X+21Y=130， X，Y均属自然数，X、Y只能取1-4，即可得到答案了。所以最好的答案应该II充分I不充分

JBG

您好！您还有数学PREP题吗？我一直想下载，可是找不到，麻烦能传一份给我吗？不胜感激啊  crazyjacky1986{a} sina.com