Re: [計量] GWD-PS幾題

看板GMAT (GMAT入學考試)作者時間17年前 (2007/11/21 23:59), 編輯推噓3(301)
留言4則, 2人參與, 最新討論串2/2 (看更多)
※ 引述《mimiwei955 (霖)》之銘言: : 1. : Three printing presses, R, S, and T, working together at their respective : constant rates, can do a certain printing job in 4 hours. S and T, : working together at their respective constant rates, can do the same job : in 5 hours. : How many hours would it take R, working alone at its constant rate, : to do the same job? : A. 8 : B. 10 : C. 12 : D. 15 : E. 20 題目說的都是同一個工作 所以可以得到以下式子 (1)1/R+1/S+1/T=1/4 (2)1/S+1/T=1/5 (1)-(2)= 1/R=1/4-1/5 R=20 : 2. : This year Henry will save a certain amount of his income, and he will spend t : he rest. Next year Henry will have no income, but for each dollar that : he saves this year, he will have 1 + r dollars available to spend. : In terms of r, what fraction of his income should Henry save this year so that : next year the amount he was available to spend will be equal to half : the amount that he spends this year? : A. 1/(r+2) : B. 1/(2r+2) : C. 1/(3r+2) : D. 1/(r+3) : E. 1/(2r+3) : 兩題答案都是E : 麻煩大家幫我解答 : 萬分感謝!!! 依題意之道income的用途只有save 和spend 設I=Sa+Sp 問今年要存占income多少比例的錢 明年才可以花1/2今年花的錢 Sa(1+r)=1/2Sp 2Sa(1+r)=Sp 兩邊相加Sa 2Sa(1+r)+Sa=Sp+Sa Sa(2+2r+1)=I Sa/I=1/(2r+3) -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 219.81.167.234 ※ 編輯: chengyuyang 來自: 219.81.167.234 (11/22 00:15)

11/22 11:25, , 1F
非常感謝~原來1+r是比例的含意....難怪我作不出來~哈
11/22 11:25, 1F

11/22 11:37, , 2F
1+r在這裡應該是利息的觀念唷
11/22 11:37, 2F

11/22 11:37, , 3F
今年存sa的錢 依題意 明年變成sa(1+r)
11/22 11:37, 3F

11/22 14:13, , 4F
原來如此~謝謝C大^^
11/22 14:13, 4F
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