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标题: PREP1-DS-Q214 [打印本页]

作者: evelyn205205 时间: 2011-7-22 22:43
标题: PREP1-DS-Q214
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.

答案是D。
这道题怎么一个做题思路呢？
先谢谢各位NN哈

作者: garlicwu 时间: 2011-7-23 02:47
说厚板的价格和长度成比例，设cost=L*p1；and also与厚度成比例，设cost=T*p2
所以 cost^2=L*T*p1*p2，设p=p1*p2
1）2*0.2*p的平方根 - 2*0.1*p的平方根 = 160，能算出p，再根据cost^2=L*T*p算出厚板价格
2）同理1

作者: evelyn205205 时间: 2011-7-23 13:48
谢谢咯~

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