prep数学ps题

zhongyaya

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 a certain number of cartons, what percent of the cartons were sealed by the machine working at the faster rate?

题目问的问题不太明白什么意思

liexodus

就是问两个一起做，在同样的时间里，快的那个完成了总的工作量的百分之几。
你可以列个等式来的，设完成A工作量，时间T
T(K/8+k/4)=A

T=8A/3K

所以快的那个在时间T里面就是完成了8A/3K×K/4=2/3A

liexodus

这种题可能就是这种思维。