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标题: 请教两道11月2号的韩国JJ数学题（急） [打印本页]

作者: elainefang 时间: 2009-11-4 01:33:28 标题: 请教两道11月2号的韩国JJ数学题（急）

是看11月2号的韩国机经，这两道实在不会做，11月14号休斯顿考试，不知道会不会考到这么难的题目啊
1. In a certain country a person is born every 3 seconds and a person dies every 10 seconds. Therefore the birth and death rates account for a population growth rate of one person every:

a. 3 1/3 sec
b. 4 2/7 sec
c. 7 sec
d. 11 2/3 sec
e. 13 sec

4. By weight liquid A makes up 7 percent of solution I and 14.5 percent of solution II. If 3 grams of solution I is mixed with 2 grams of Solution II, then the liquid A accounts for what percent of the weight of the resulting solution?

a. 6.09%
b. 10%
c. 10.75%
d. 21.5%
e. 50%

作者: wbgqm 时间: 2009-11-4 01:46:47

这些不是机经题吧，都是老陈书上的题

作者: tianrunhe 时间: 2009-11-4 02:08:32

1. After 30 secs, 10 people was born, 3 people was died, so 30 / (10 - 3) = 30/7
2. (3 * 7% + 2 * 14.5%) / (3+2) = 10%

作者: scott_umac 时间: 2009-11-4 02:26:59

The same as LS

作者: elainefang 时间: 2009-11-5 01:44:39

THanks for your answer

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