PTT職涯區 / GRE (GRE入學考試)

[計量] 計量數學問題一問...@@

看板GRE (GRE入學考試)作者 (pepe)時間14年前 (2011/07/06 23:46), 編輯推噓1(1推 0噓 8→)
留言9則, 5人參與, 最新討論串1/2 (看更多)
題目是@@! worker W produces n units in 5 hours. Workers V and W, working independently but at the same time, produce n units in 2 hours. How long would it take V alone to produce n units? A:1hr26min B:1hr53min C:2hr30min D:3hr20min E:3hr30min 答案是D...@@煩請各位高手指導一下Orz -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 140.112.121.239
推
07/06 23:50, , 1F
W產能=n/5 unit/hr, (W+V)產能=n/2 unit/hr
07/06 23:50, 1F
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07/06 23:52, , 2F
所以V產能=n/2-n/5=3n/10 要10/3hr可產n units
07/06 23:52, 2F
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07/06 23:55, , 3F
W:每小時X->五小時-> 5X=n V:每小時Y
07/06 23:55, 3F
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07/06 23:56, , 4F
W和V兩小時共 2X+2Y=n 解聯立求Y
07/06 23:56, 4F
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07/06 23:57, , 5F
10Y/3=n 所以是3 1/3小時
07/06 23:57, 5F
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07/06 23:59, , 6F
謝謝您的指導~~感激不盡!!!!^~^
07/06 23:59, 6F
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07/07 00:27, , 7F
反正n為任何數 或許直接帶個值 會來的比較直覺
07/07 00:27, 7F
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07/09 00:42, , 8F
W:2n in 10hrs,W+V:5n in 10hrs=>V:3n in 10hrs
07/09 00:42, 8F
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07/09 00:44, , 9F
=>n in (10/3)hrs
07/09 00:44, 9F
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