GWD30-12(total 31 套題)

[dylanchang]

Working alone at its constant rate, machine K took 3 hours to produce 1/4 of the units produced last Friday. Then machine M started working and the two machines, working simultaneously at their respective constant rates, took 6 hours to produce the rest of the units produced last Friday. How many hours would it have taken machine M, working alone at its constant rate, to produce all of the units produced last Friday?

A. 8
B. 12
C. 16
D. 24
E. 30

Answer: D

M機器完成 1/4的工作 用了3小時
之後 跟另外兩台機器一起完成剩餘部份 用了6小時
問如果M自己作所有工作要幾小時

看完題目 覺得很怪 不就很簡單 1/(1/12)=12 後面講一堆廢話 結果答案不對啦 為啥是D 請各位大大幫幫忙 難道是我翻譯有問題

------------------------------------------------------------
對不起 我懂了 不要理我
耍粗心 k m 不分的 果然太緊張就會很粗心
還是謝謝 navywhite0425 花時間解這題

[navywhite0425]

我是用很笨的方式寫的
你看看嚕

k: 3h 完成了1/4 => 1h 完成了1/12 => 6h 完成了1/2
k+m: 6h 完成了3/4

so, m 6h完成了3/4-1/2=1/4
thus, m需要24小時來完成1個工作量

醬可以嘛??