GMAT数学模拟练习题及答案【5】

　　Two water pumps,working simultaneously at their respective constant rates, took exactly 4 hoursto fill a certain swimming pool. If theconstant rate of one pump was 1.5 times the constant rate of the other, how manyhours would it have taken the faster pump to fill the pool if it had workedalone at its constant rate?

　　A) 5

　　B) 16/3

　　C) 1/2

　　D) 6

　　E) 20/3

　　题目翻译：两个水泵以恒定的效率同时工作，蓄满一个游泳池需要4小时，如果其中一个水

　　泵的效率是另一个泵的1.5倍，效率高的水泵单独给游泳池蓄水需要多少小时?

　　思路点拔：解方程

　　题目全解：设效率快的水泵每小时蓄水x,单独蓄水需要a小时，则方程为：(x+x/1.5)*4=ax，

　　解得a=6+2/3

　　A glass wasfilled with 10 ounces of water, and 0.01 ounce of the water evaporated each dayduring a twenty-day period. What percentof the original amount of water evaporated during this period?

　　A. 0.002%

　　B. 0.02%

　　C. 0.2%

　　D. 2%

　　E. 20%

　　参考答案：D

　　题目翻译：10盎司水，每天蒸发0.01盎司，20天后蒸发了百分之多少的水?

　　题目全解：(0.01*20/10)*100%=2%