[問題] 陳向東數學一些問題

看板GRE (GRE入學考試)作者GOKU123 (GOKU)時間14年前 (2012/04/22 22:46)推噓1(1推 0噓 4→)

留言5則, 2人參與討論串1/3 (看更多)

p.166 第25題 A rectangular floor with an area of 12 square meter is drawn to scale with 2 centimeters representing L meter. QA: The area of scale drawing of the floor OB: 24 square centimeters Ans: (A) QA>QB 問題: 如果把 2 cm 縮小為 L m, 設原圖形兩邊長為x,y. 新圖型的邊長應為2x/L,2y/L xy=12 那面積變成4xy/L^2 = 48/L^2 那麼大小不就取決於L? 答案應該是(D)? p.255 第6題比大小 For the line with equation y-ax+b, ab≠0, the x-intercept is twice the y-intercept. QA:The slope of the line OB:1/2 答案是B 問題是:X截距為Y截距兩倍，斜率不是應該會有正或負?感覺斜率應該是±1/2? p.257 第17題 In the xy-plane, line k is a line that does not pass through the origin. Which of the following statements individually provide(s) sufficient additional information to determine whhether the slope of line k is negative? Indicate all such statements. (A) The x-intercept of line k is twice the y-intercept of line k (B) The product of the x-intercept and the y-intercept of line k is positive. (C) Line k passes through the points(a,b) and(r,s), where(a-r)(b-s)<0 Ans:ABC 問題:(A)裡面同樣截距是兩倍，斜率應該會是有正有負吧? p.258 第20題 If the total of commuters to Country W is twice the number to Country Z, and if the average number of vehicles that transport commuters daily to Country W is 30,000, what is the approximate average number of vehicles that transport commuters daily to Country Z? Ans:(A) 12,000 問題:本題有附圖，但我覺得題目跟圖表無關算法為:total=average*days 而days為常數, 所以 total(W)為total(Z)的兩倍;那average(Z)就應該是average(W)的1/2 30000/2=15000---(B)選項嗎? p.260 第9題題目是不是沒給完整阿@@? p.261 第18題 George earned 80,85 and 90 on the first three test in his geography class. Because he didn't have time to study, he decides to guess randomly on the final test. That test has ten true-false questions, each worth 10 points. What is the probability his final average is more than 85? (A)12/2^8 (B)11/2^8 (C) 12/1024 (D) 11/1024 (E) 0.5 Ans:(D) 問題:不會算= =? 算法: 期末平均要 >85 代表期末考要考90或100 所以要對九題以上 => C十取九 * (1/2)^9 ....沒答案XD -------------------- 感謝解答QQ 另外想問一下 1.數學做陳向東就好了嗎還是有什麼其它適合的題目可以再練習? 2.一些美國常用的單位換算 feet,ounce,dime等需要背嗎? 3.大家正常的話，數學應該留幾分鐘檢察? 4.圖表問題，因為不像書本可以用尺去對照圖表的數據，這在機考有影響嗎? 感激不盡!!!^^" -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 1.173.104.86