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想要请教各位一道ds题
274. A clothing manufacturer makes jackets that are wool or cotton or a combination of wool and cotton. The manufacturer has 3,000 pounds of wool and 2,000 pounds of
cotton on hand. Is this enough wool and cotton to make at least 1,000 jackets?
1. Each wool jacket requires 4 pounds of wool, and no cotton.
2. Each cotton jacket requires 6 pounds of cotton, and no wool.
答案是c。我可以理解1和2单独都不是充分的，但是不懂为什么1和2一起时是充分的。
答案解释是这样的：
1. Given that each wool jacket requires 4 pounds of wool and no cotton, then at most a total of 750 wool jackets can be made (because = 750), and possibly no other jackets. Therefore, it is possible that there is enough wool and cotton to make at least 1,000 jackets (for example, if there is enough cotton to make 250 cotton jackets) and it is possible that there is not enough wool and cotton to make at least 1,000 jackets (for example, if there is less than the amount of cotton needed to make 250 cotton jackets); NOT sufficient.
2. Given that each cotton jacket requires 6 pounds of cotton and no wool, then at most a total of 333 cotton jackets can be made (because rounding down to the nearest integer gives 333), and possibly no other jackets. Therefore, it is possible that there is enough wool and cotton to make at least 1,000 jackets (for example, if there is enough wool to make 667 wool jackets), and it is possible that there is not enough wool and cotton to make at least 1,000 jackets (for example, if there is less than the amount of wool needed to make 667 wool jackets); NOT sufficient.
Taking (1) and (2) together, there is enough wool and cotton to make 750 wool jackets and 333 cotton jackets for a total of 1,083 jackets.
题干没有告诉我们羊毛和棉混着做衣服时候各需多少羊毛和棉，那怎么能够判断一定能够或者不能够做1000件衣服呢？
我在网上查了，发现没有对该题的讨论，诚心求教，谢谢各位。
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发表于 2017-5-20 11:48:25
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