[計量] PP1-ps-190

[Automatic620 (我很乖)]

pp1-ps-190

Pumps A, B, and C operate at their respective constant rates.  Pumps A and B,

operating simultaneously, can fill a certain tank in 6/5 hours; pumps A and

C, operating simultaneously, can fill the tank in  3/2  hours; and pumps B and

C,operating simultaneously, can fill the tank in 2 hours.  How many hours does

it take pumps A, B, and C, operating simultaneously, to fill the tank?

(A) 1/3

(B) 1/2

(C) 2/3

(D) 5/6

(E) 1


我的算法是把這三式相加/2 因為a b c各有個重複，不過....還沒算出來就知道是錯的了


想了很久又想不出來orz 也不知道該怎麼算 囧

答案是E 有沒有高手能指教一下?

感謝

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◆ From: 59.121.145.39
※ 編輯: Automatic620    來自: 59.121.145.39        (09/20 21:22)
推 DreamKite:(5/6 + 2/3 + 1/2)/2 = 1  不就是答案 ?
→ DreamKite:要記得用倒數喔!
→ Automatic620:我也是這樣算呀！！！囧 可是我怎麼算不出是1??
→ DreamKite:.......那~這是國中數學不好.........
→ Automatic620:我再算一次orz
→ Automatic620:1了耶!! 算出來了，抱歉真的是耍笨了
推 DreamKite:不會啦~反正我只有數學好 V 爛個半死