Re: [計量] 請問兩題PP的問題

看板GMAT (GMAT入學考試)作者a1985526 (new)時間17年前 (2007/11/04 12:50)推噓1(1推 0噓 0→)

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※ 引述《dedust ( ︠ 臈臈ﰩ》之銘言： : On a certain sight-seeing tour, the ratio of the number of women to the : number of children was 5 to 2. What was the number of men on the sight-seeing : tour? : (1) On the sight-seeing tour, the ration of the number of children to the : number of men was 5 to 11. : (2) The number of women on the sight-seeing tour was less than 30 sol: 已知 w:c = 5:2, 求 the number of men on the sight seeing tour (1) c:m = 5:11 ---> the ratio of women to children to men = 25:10:22; however, knowing the ratio does not help us know the exact number of men, so option 1 is invalid. (2) the number of women < 30 (條件不足) 25:10:22 中, 25r <30 ---> 5r < 6 ---> r = 1 therefore, there were 22 men, 25 women, and 10 children. ------------->C : Ans:C : Machines X and Y work a their respective constant rates. How many hours does : it take machine Y, working alone, to fill a production order of a certain : size than 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. Sx = 1/x ; Sy = 1/y 求 Ty - Tx (1) 1/x + 1/y = 3/2 * 1/x 1/y = 3/2x - 1/x = 3/2x - 2/2x = 1/2x y = 2x (2) 1/y *2 = 1/x 2/y = 1/x 2x = y 合併(1) 及(2), 充其量知道 x machine 及 y machine 的比例, 對於兩者所需的時間還是沒有幫助的------------------------------->(E) : Ans:E ---------------------------------- 我盡力回答了 @_@ -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 61.66.187.115 ※ 編輯: a1985526 來自: 61.66.187.115 (11/04 12:59)