Re: [計量] 我還有問題想要請教?

看板GRE (GRE入學考試)作者mathhaven (多得一點分多馬斯)時間16年前 (2010/05/12 15:33)推噓0(0推 0噓 0→)

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※ 引述《shenglan (拼了!GRE)》之銘言： : 1.the average (arithmetic mean) of a set of 12 numbers,which includes 34,is N : if 34 is removed the set and 38 is added to the set,what is the average of : the new set of numbers,in terms of N? : a)N+1/3 b)N+6/19 c)N+4 d)N+6 e)12N+4 把34拿掉放回38所有總和多了4 所以平均多了4/12+N ans: a : 2.a train travels from city X to city Y in 3 hours and 30 mins at an average : speed of 60 mile per hour.if the train returns at an average speed of 50 : miles per hour,how lonf does the return trip take? : a)2 hr 55 min b)3hr 40 min c)4 hr 12 min d)4 hr 32 min e)4 hr 40 min 先算出X到Y的距離: 60(時速)*3.5(花費時間) = 210 miles 再算回程所需時間: 210/50 = 4.2(hr) = 4 hr and 12 min ans: c : 3.if 18 identical machines required 40 days to complete a job,how many fewer : days would have been required to do the job if 6 addirional machines of the : same type had been used from the beginning? : a)10 b)13又1/3 c)16 d)26又2/3 3)36 假設 a job = X = 18*40(需要花費這麼多力氣才能完成) 加入6個新的機器後， X/(18+6) = 18*40/24 = 30 (day) 原題問加入後會比之前少幾天，所以是 40-30 = 10 (day) ans: a : 4.of the positive integers that are multiples of 30 and are less than or equal : to 360,what fraction are mutiples of 12? : a)1/6 b)1/5 c)1/3) d)2/5 e)1/2 題目是說 1.小於等於360中先挑出30的倍數，2.這些挑出的數字中有多少是12倍數 1. 30, 60, 90, 120, 150,…, 360共12個數字 2. 從1.中挑出12的倍數: 60, 120, 180, 240, 300, 360 共6個 ans: e : **我是有把數字列出來30的倍數且小於360的有:30,60,90,120,150,180,210,240,270 : 300,330,360可是第二句就不大懂意思了?是翻成12倍數的分數是甚麼嗎?@@" : 可是我除了1/2的答案，也要算出1/5耶!!! : 5.a decrease of 1 in which of the factors bove would result in the greatest : decrease in the product? : a)11 b)13 c)17 d)19 e)23 看無 : 6.worker W produce n units in 5 hours. wokers V and W,working independently : but at the same time,produce n units in 2 hours.how long would it take V : alone to produce n units? : a)1 hr 2 min b)1 hr 53 min c)2 hr 30 min d)3 hr 20 min e)3 hr 30 min W每個小時完成n/5 units,兩個人一起做花了2hrs W完成了 n/5*2units 所以V完成了n-n/5*2 = 3n/5 units in 2 hours so V can produce 3n/10 units per hour 題目問V自己一個人要做多久: n/(3n/10) = 10/3 hrs = 3 hr 20 min. ans: d : **圖表題我也錯很多，可是不知道要怎麼問?@@" : 謝謝你們的解釋!!!^^ -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 123.193.208.247