Re: [計量] 數學問題~

看板GRE (GRE入學考試)作者BlueKidds (追求卓越近乎苛求)時間18年前 (2007/10/31 22:25)推噓0(0推 0噓 0→)

留言0則, 0人參與討論串2/2 (看更多)

※ 引述《hsingchih (請賜我GRE高分吧!!)》之銘言： : 1. An emergency vehicle travels 10 miles at a speed of 50 miles per hour. : How fast must the vehicle travel on the return trip if the round-trip : travel times is to be 20 minutes? : (A) 55 mph : (B) 60 mph : (C) 65 mph : (D) 70 mph : (E) 75 mph : Ans: E 距離= 速度 * 時間 10 = 50 * h h= 1/5 hour = 12 mins 回程只能跑8 mins 故 10 = V * 8/60 V= 600/8=75 : 2. The sum of 2 numbers, x and y, equals twice their product. : If x=3, what is the value of y? : (A) 1/8 : (B) 3/5 : (C) 3/2 : (D) 5/3 : (E) 7/3 : Ans: B x+y=2xy 3+y=2*3*y y=3/5 : 3. Among all isosceles triangles RST having the measure of angle S equal to : 40。, what is the largest possible measure for angle R? : (A) 40。 : (B) 70。 : (C) 90。 : (D) 100。 : (E) it cannot be determined from the information given. : Ans:D 等腰三角形其中一角40 可能為腰可能為頂角若為腰: 頂角= 180 - 80 = 100 若為頂: 腰 = (180 - 40)/2 = 70 選D : 4. S is the sum of three consecutive integers, the greatest of which is x. : In terms of S, which of the following is the sum of three consecutive : integers, the least of which is x? : (A) S-6 : (B) S-3 : (C) S+3 : (D) S+6 : (E) 2S : Ans: D : 不知道那做錯了, 設三個數分別為 x, x-1, x-2 : x+(x-1)+(x-2)=S : 3x-3=S 3x=S+3 x=S+3/3 : 是我誤解題目的意思嗎?? 請高手幫幫忙~~謝謝~ 最大的數是x 三數為 x-2, x-1, x的和為 S, 也就是 3x-3 現在改成最小的是x, 三數為 x, x+1, x+2也就是3x+3 所以3x+3 = 3x-3 +6=S+6 : 5.Circle F has circumference 4 : Cloumn A The radius of F : Cloumn B 1 : Ans: B : Cloumn A 不是應該為4/1.414=2.8 半徑=1.4嗎? 為什麼答案會是Cloumn B比較大呢? 1.414是更號2 , 圓周率是3.414 : 6. r/s= -1 : Cloumn A r+s/s : Cloumn B rs : Ans: A (r+s)/s= r/s + s/s = -1 + 1 = 0 r, s都不為0而且一正一負所以0比較大 : 7.Nine pieces of paper numbered consecutively from 1 to 9 are put into a hat. : If one piece of paper is drawn at random from the hat, what is the probability : that it will have an even number? : (A) 1/9 : (B) 2/9 : (C) 4/9 : (D) 1/2 : (E) 5/9 : Ans: C : 機率問題完全不知道該如何回答,請高手教教我如何解答機率題~謝謝~ GRE幾乎都只有古典機率機率 = (事件數) / 母體數九片取一片其中數字為偶數的機會母體 = 9 事件 = 4 答案 = 4/9 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 59.104.4.187