一道prep DS求助

BryceL

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.

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

lzc95232

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

DD_c

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