Re: [計量]PP1-DS-41.76.93

看板GMAT (GMAT入學考試)作者sacul (江東小肉圓)時間16年前 (2008/08/16 09:55)推噓1(1推 0噓 0→)

留言1則, 1人參與討論串2/2 (看更多)

※ 引述《vitality (有捨才有得...)》之銘言： : 41.Machines X and Y work at theier 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)Machine 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. : Ans:E 設總工程為1，X的工作效率為x，Y的工作效率為y (1) 1/(x+y)=(2/3)*(1/x) 化簡得 2y=x ...insuff (2) 1/y=2*(1/x) 化簡得 2y=x ...insuff 又(1)(2)聯立還是只有一條方程式 ...insuff : 76.Is the integer K divisible by 4? : (1) 8K is disvisible by 16. : (2) 9k is disvisible by 12. : Ans:B (1)8K/16=K/2...0 只知道K能被2整除 ...insuff (2)9K/12=3K/4...0 由於前面的3不是4的倍數，所以後面的K肯定能被4整除...suff : 93.If the integer n is greater than 1, is n equal to 2? : (1) n has exactly two positive factors. : (2) The difference of any two distant factors of n is odd. : 這題不懂的是第二個選項 : 如果n=4 factors有1.2.2或是1.4 這樣2-1或4-1 不也是odd的嗎? : Ans: B (1)剛好只有2個因數的整數 2,3,5,7,11....insuff (2)正整數有2種，奇數跟偶數奇數:因數包含本身和1，2者相減必定是偶數 ex:3-1,5-1,7-1... 超過2的偶數:因數包含本身和2，2者相減必定也是偶數 ex:4的因數:1,2,4 =>4-2 6的因數:1,2,3,6 =>6-2 正整數排除以上只剩2了...suff -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 61.228.108.135