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标题: 一道prep DS求助 [打印本页]

作者: BryceL 时间: 2019-11-12 21:27
标题: 一道prep DS求助
The cost of a square slab is proportional to its thickness and also proportional to the square of its length. What is the cost of a square slab that is 3 meters long and 0.1 meter thick?

(1) The cost of a square slab that is 2 meters long and 0.2 meter thick is $160 more than the cost of a square slab that is 2 meters long and 0.1 meter thick.
(2) The cost of a square slab that is 3 meters long and 0.1 meter thick is $200 more than the cost of a square slab that is 2 meters long and 0.1 meter thick.

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.

作者: lzc95232 时间: 2019-11-12 22:47
本人数学也不好，说说自己的理解,楼主听听看
因为这个正方形木块和他的长度厚度成比例，所以把条件带进去算下看看：
条件1：2m长，0.2厚，所以这块的体积是2*2*0.2=0.8m^3,
         2m长，0.1厚，2*2*0.1=0.4m^3
         所以差是0.8-0.4=0.4，这0.4m^3差了160块，可以算出每0.1m^3差了40块，所以3m长，0.1厚的可以算出来，3*3*0.1=0.9m^3
         所以结果是9*40=360块
条件2和条件1除了数都一样所以方法也一样
所以应该选D

作者: DD_c 时间: 2019-11-14 03:13
条件1：已知 t & l，可求$。有已求$和proportional关系式，就可以求未知$
条件2：一样。已知 t & l，可求$。有已求$和proportional关系式，就可以求未知$
所以俩都行

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