几个prep题

wayhas

204.
            19682-!-item-!-187;#058&012407

    

On a certain sight-seeing tour, the ratio of the number of women to the
number of children was 5 to 2.  What was
the number of men on the sight-seeing tour?

    

(1)  On the sight-seeing tour, the
ratio of the number of children to the number of men was 5 to 11.

    

(2)  The number of women on the sight-seeing tour
was less than 30.

52.   6641-!-item-!-187;#058&005112

                

In the circle above, PQ is parallel to diameter OR, and OR has length
18.  What is the length of minor arc PQ  ?

                

(A)  2∏

                

(B)  9∏/4

                

(C)  7∏/2

                

(D)  9∏/2

                

(E)  3∏

                

                    

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142.
                                                    14580-!-item-!-187;#058&010013[D1] 

                                        

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

                                        

                                            

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还有20天就考了，半年了每天8+小时的学。。数学还是48，49徘徊。。ver更是一塌糊涂...GWD-TN-24每次都错10个以上。前两天做15套一下错了28个，崩溃啊！！谢谢大家了，帮帮忙解答下，拜托！！