[問題]新 PP2-37

[tandy]

working alone at its own constant rate, a machine seals k cortons in 8 hours, and working alone at its own constant rate, a second machine seals k cortons in 4 hours. If the machines, each working at its own constant rate and for the same period of time, together sealed a certain number of carton, what percent of the cartons were sealed by the machine working at the faster rate?
(A)25%
(B)33 1/3%
(C)50%
(D)66 2/3%
(E)75%
答案是(D)
請問各位大大這題到底是在問啥?百思不解..... 拜託大家幫忙 謝謝!!

[stwang]

題目是說完成一件事 第一台機器做8小時 第二台機器做4小時
如果這兩台機器依照自己的速度一起完成一件事 則速度快的那台機器所完成這件事的比例是多少??

算法:速度快的機器速率是1/4
1/4/(1/4+1/8)=2/3=66.68%


給你參考參考

[tandy]

懂了懂了~~ 真多謝!!!