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题库 / Prep2007E1-DS-214
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.
cost表达式为什么不是cost=al^2+bt?, a和b都是constants
为什么不能列方程嘞？
mark
（1）2米长0.1米厚的正方体$160---1米长0.1米厚的正方体$80---3米长0.1米厚的正方体$240
（2）1米长0.1米厚的正方体$200---3米长0.1米厚的正方体$600
两米长的正方形方块 切除一个一米长的正方形方块 不是除以2 吧
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然后我用楼下的方法验证了一下，看看答案是不是一样
按照列方程的方法求出出来的k=400，然后再代入方程求得的最终结果是360.
两种算法的答案是不一样的。
啊～～我知道了。不可以按照这种设方程的方法啦，虽然答案都是充分，但是这个计算方法不对。
根据条件1，2*0.2的立方体比2*0.1的立方体多花160块，其实2*0.2是两个2*0.1的立方体叠在一起，也就得出一个2*0.1的立方体的成本是160，然后再把2*0.1的立方体平均分成两块，1*0.1的成本是80，那题目中3*0.1=3*80=240。
条件2也是同理，总之就是把它分成1*0.1的小立方体。
原来是这样
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题目的难度主要在理解这句话The cost of a square slab is proportional to its thickness and also proportional to the square of its length. 如果按照楼下的这种说法是把它理解成与立方体的体积成比例就好懂了，但是我不知道能不能这么理解。
设Cost=a*l^2*t
cost= L^2*T