4. in a stack of boards at a lumber yard, the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack.how many boards are in the stack?
a 38 b 36 c 35 d 34 e 32 答案是D 是不是顺数是第20个 倒数是 第16 个？为啥是 34 呢？？？ 42 the rate of a certain chemical reaction is directly propotional 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
答案是D 如何列式子？A 和B 是相加关系吗？ 148 Amy's grade was the 90th percentile of the 80 grades for her class.Of the 100 grades from another class, 19 were higher than Amy's, and the rest were lower.If no other grade was the same as Amy's grade, then Amy's grade was what percentile of the grades of the 2 classes combined.
a 72th b 80th c 81th d 85th e 92nd
答案是D 怎么做？
1.Before being simplified, the instruction for computing income tax in Country R were to add 2 percent of one's annual income to the average (arthmetic mean ) of 100 of country R's currency and 1 percent of one's annual income. what is the simplifed formula for computing the income tax,in Country R's currency, for a person in that country whose annual income is I ?
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发表于 2009-11-28 14:02:38
