1、The rate of a certain chemical reaction is directly proportaional 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%, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?
2、Each of the students in a certain class received a single grade of P,F or I. What percent of the students in the class were females?
(1) of those who received a P, 40% were females.
(2) of those who received either an F or I, 80% were males.
正确答案：E
3、Each employee of Company Z is an employee of either Division X or Division Y, but not both. If each division has some part-time employees, is the retio of the number of full-time employees to the number of part-time employees greater for Division X than for Company Z?
(1) The ratio of the number of full-time employees to the number of part-time employees is less for Division X than for Company Z.
(2) More than half of the full-time employees of Company Z are comployees of Division X, and more than half of the part-time employees of Company Z are employees of Division Y.
正确答案：D
4、If x,y,z are integers greater than 1, what is the value of x+y+z?
(1) xyz = 70
(2) x / yz = 7/ 10作者: songxuebest 时间: 2011-3-18 20:53
1、The rate of a certain chemical reaction is directly proportaional 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%, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?
Rate = [A]*[A]/[B]
So [A]*[A]/[B] = [x*A]*[x*A]/[2B]
x*x = 2
x = 1.414
So A increases around 40%作者: songxuebest 时间: 2011-3-18 21:02
2、Each of the students in a certain class received a single grade of P,F or I. What percent of the students in the class were females?
(1) of those who received a P, 40% were females.
(2) of those who received either an F or I, 80% were males.
category P F I
male A B C
female a b c
a/(a+A) =.4
(B+C)/(B+C+b+c) = .8
Do you know the value of (a+b+c)/(A+B+C+a+b+c)?
Hell, NO!作者: soojin3215 时间: 2011-3-19 19:39
谢谢！！前两个都明白了。作者: sumerlaws 时间: 2011-3-20 08:03
4.
(1) 70=7*5*2作者: songxuebest 时间: 2011-3-20 21:49
3、Each employee of Company Z is an employee of either Division X or Division Y, but not both. If each division has some part-time employees, is the retio of the number of full-time employees to the number of part-time employees greater for Division X than for Company Z?
(1) The ratio of the number of full-time employees to the number of part-time employees is less for Division X than for Company Z.
(2) More than half of the full-time employees of Company Z are comployees of Division X, and more than half of the part-time employees of Company Z are employees of Division Y.
