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1. The rate of a certain chemical reaction is directly proportional to the square of the concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is increased by 100 percent, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged? (A) 100% decrease (B) 50% decrease (C) 40% decrease (D) 40% increase (E) 50% increase
Answer: D 题目什么意思啊？没看懂~~
2. If x is positive, which of the following could be the correct ordering of 1/x, 2x, and x^2 ? I) x^2 <2x<1/x II) x^2 <1/x<2x III) 2x<x^2 <1/x (A) None (B) I only (C) III only (D) I and II only (E) I , II and III
Answer: D 请问这种题目一般要考虑那几个方面才能保证不会漏掉任何情况啊？
3. If x is a positive number less than 10, is z greater than the average (arithmetic mean) of x and 10 ? (1) On the number line, z is closer to 10 than it is to x. (2) z = 5x
Answer:A
4. A contractor combined x tons of a gravel mixture that contained 10 percent gravel G, by weight, with y tons of a mixture that contained 2 percent gravel G, by weight, to produce z tons of a mixture that was 5 percent gravel G, by weight. What is the value of x ? (1) y = 10 (2) z = 16
Answer: D 怎么算出来的呢？我选择c
Answer: D 怎么算出来的呢？我选择c
Answer:A
4. A contractor combined x tons of a gravel mixture that contained 10 percent gravel G, by weight, with y tons of a mixture that contained 2 percent gravel G, by weight, to produce z tons of a mixture that was 5 percent gravel G, by weight. What is the value of x ? (1) y = 10 (2) z = 16
Answer: D 怎么算出来的呢？我选择c
Answer: D 怎么算出来的呢？我选择c
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发表于 2007-12-30 18:05:00
