GMATPre-T1-PS

[lucyyeh]

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 present 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D,
不好意思，數學太弱，不知道怎麼算出來的，請各位高手費心指點一下!
謝謝!

[Frankts]

題目的意思應該是說(A^2)*(1/B)=constant
問當B濃度增加一倍時 A應該要多少才能維持固定
簡化後 A^2=2--------> A=1.4左右
答案..增加40%
這題應該是考閱讀 跟數學沒關係