[求助]prep一道工作效率的题目

9tian

这道题读的不是特别明白：

working alone at its own constant rate, a machine seals K cartons in 8 hours, and working alone at its own constant rate, a second machine seals K cartons in 4 hours. If the two machines, each working at its own constant rate and for the same period of time, together sealed at certain number of cartons, what percent of the cartons were sealed by the machine working at the faster rate?

答案是 【66×（2/3)】%

不太明白这个比率是谁在和谁做比较。谢谢

geerer

是拿快的那个机器糊的carton比上所有的carton

jikuren

慢机器完成1个纸箱的同时，快机器能完成2个纸箱，题问快机器完成量是两台机器完成总量的百分比，答案是2/3，或66.67%.