Re: [計量] Two tanks, X and Y, are filled ...

看板GRE (GRE入學考試)作者passthrough (小笨)時間17年前 (2008/11/10 01:05)推噓0(0推 0噓 0→)

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我只會解三題... 2, 4兩題給其他高手解吧~ ※ 引述《tkmax (事事如意)》之銘言： : 做練習遇到的幾題想不出來的問題... : 拜託各位大大幫解~~ 謝謝 <(_ _)> : 1. Two tanks, X and Y, are filled to capacity with jet fuel. : Tank X holds 600 gallons more than tank Y. : If 100 gallons of fuel were to be pumped from each tank, : tank X would then contain 3 times as much fuel as tank Y. : What is the total number of gallons of fuel in the two full tanks? : Ans: 1400 設Tank X holds X gallons Tank Y holds Y gallons 則 X = Y + 600.....式1 又 X - 100 = 3 ( Y - 100 ).....式2 將式1代入式2: ( 600 + Y) - 100 = 3 ( Y - 100 ) 得Y = 400 則X = Y + 600 = 1000 所以 X + Y = 1000 + 400 = 1400 : 2. If the value if the expression above is to be halved by : doubling exactly one of the five numbers a,b,c,d, or e, : which should be double? : Ans: d 看不懂... : 3. A part-time employee whose hourly wage was increased by : 25 prescent decided to reduce the number of hours worked : per weeks so that the employee’s total weekly income would : remain unchanged. By what percent should the number of hours : worked be reduced? : Ans: 20% 設原本wage為W, 原本工作時間為H 後來wage為 W*(1+25%) , 後來工作時間為H' 則 W * H = 1.25W * H' 則 H': H = W : 1.25W = 80% 表後來工作時數為原來的80%, 故減少了20% : 4. For telephone calls between two particular cities, a telephone : company charges $0.40 per minute if the calls are placed : between 5:00 a.m. and 9:00 p.m. and $0.25 per minute if the c : alls are placed between the two cities placed at 1:00 p.m. : was $10.00, how much would a call of the same duration have cost : if it had been placed at 11:00 p.m.? : Ans: $6.25 看不懂... : 5. If X and Y are sets of integers, X#Y denotes the set of integers : that belong to set X or set Y , but not both. : If X consists of 10 integers, Y consists of 18 integers, : and 6 of the integers are in both X and Y, then X#Y consists : if how many integers? : Ans: 16 畫兩個圓相交叉就知道了答案等於X + Y - 2*(X交集Y) = 10 + 18 - 2*6 = 16 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 61.216.5.93