[計量] PP1-DS-41

[clearfuture (really?)]

Machines X and Y work at their respective constant rates.
How many more hours does it take machine Y, working alone,
to fill a production order of a certain size than it takes
machine X, working alone?

(1) Machines X and Y, working together, fill a
    production order of this size in two-thirds the
    time that machine X, working alone, does.

(2) Machine Y, working alone, fills a production
    order of this size in twice the time that machine X, working alone, does.

(解)

設work=1, machineX=Xhour, machineY=Yhour, 問y-x=?

(1) 1/X + 1/Y = 2/3 ^ 1/X

(2) 1/Y = 2^ 1/X

答案是E

可是直覺上兩個變數，配上兩條式子，為什麼不是C ?tt.cc) 
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推 pei33ho:太神了 正要發問這題 以為自己眼花怎麼PO好了! 想要順便問
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