265.x<10, y<10, what is the range of x/y? A. 8, B.9; C. 80/9; ...........(can't remember the other two) . 小鱼评价： 题目不全，在这里不知道x,y是否大于0。 可以取无穷大或者无穷小 266.Need to use 1.5 feet metal (can't break it)to made a machine, 4 feet per roll. So need how many rolls to make 8 machines? . 小鱼评价： 题目没看明白 268.机经题：长方体内边三边长为x，y，z，厚度为一，问体积 . 小鱼评价： (x+2)(y+2)(z+2)-xyz
269.某人工作三十个小时，前x小时报酬为8元，之后每小时为12元，问那个为可能的工资值，好像是280 . 小鱼评价： x.8+(30-X).12=280 270.（62题）：what is the sum of a certain pair if consecutive odd integers? (1) at least one of the integers is negative (2) at least one of the integers is positive 作者答案及思路：ans: c . 小鱼评价： C 271.（173题）: if y is the smallest positive integer such that 3150 multiplied by y is the square of an integer, then y must be: a.2 b. 3 c.7 d. 4 e. 14 作者答案及思路：ans: e.14 . 小鱼评价： 分解因子。14 272． the surface of a certain planet reflects 80 percent of the light that strike it. the clouds around the planet then absorb 40 percent of the reflected light. what percent of the light that strikes the planet is reflected from the surface and passes trough the clouds without being absorbed? 作者答案及思路：ans: 40% . 小鱼评价： 80%*60%=48% 273． if x>1 and y>1, is x(1) x^2/(xy+x)<1 (2) xy/(y^2-y)<1 作者答案及思路：ans: e . 小鱼评价： B 274. in a meeting of 3 representatives from each of 6 different companies, each person shook hands with every person not from his or her own company . if the representatives did not shake hands with people from their own company, how many handshakes take place? 作者答案及思路： ans:135 . 小鱼评价： C2,18-6c2,3=135 275.from a group of 3 boys and 3 girls, 4 children are to be randomly selected. what is the probability that equal numbers of boys and girls will be selected? 作者答案及思路：ans: 3/5 . 小鱼评价： c2.3.c2,3/c4.6=3/5 276.the first roll of a cinema has 16 seats, the roll immediately after the first roll has 2 more seats than the first roll. every roll has two more seats than the roll immediately in front of it. the last roll of has 64 seats. how many seats does this cinema have? 作者答案及思路：ans: 1000 . 小鱼评价： 等差数列。1000 277. in the parallelogram shown, pq=4, qr=6,angleqps is 30 degree, what is the area of pqrs?
q ______________r /l / / l / p /__l____________/s （图形可能会变形，那三个1是我想画的平行四边行的高，请大家将就一下吧） . 小鱼评价： 12 278. a scientist recorded the number of eggs in each of the 10 birds' nests, what was the standard devition of the numbers of eggs in the 10 nests? (1) the averge (arithmetic mean) number of eggs for the 10 nests was 4 (2) each of the 10 nests contained the same number 作者答案及思路：ans: b . 小鱼评价： B 279. the base of a retangular solid tank is a square, the length of each side of the square is 4 meters, the altitude of the tank is 6, if there is 16 cube meters water in the tank, what is the rate of the volume of water in the tank to the volume of the retangular solid tank? 作者答案及思路：ans: 1/6 . 小鱼评价： 1/6 281.PS 有兩座城市X, Y共用一座發電廠的電. X的耗電功率(千瓦/小時) 為Y的3倍, 但兩城市的用電量一樣多, 問若X城市的用電量為發電廠的K percent, 那麼Y城市的用電量為多少percent? (這題"用電量"有兩個單字, 不好分辨不知是否代表的意義不同) 1)2/3K 2)3/2K 3)1/2K 4)2k 5)3K 這題沒做出來, 希望後人能補充 . 小鱼评价： 题目不全，没看明白 282. DS 有一平行四邊形 四個角ABCD, 四邊全等, 問是否可以知道對角線BD長為多少? 1)AD邊的長度為2 2)AC對角線長度為2 作者答案及思路：My ANS C . 小鱼评价： C
266. 4 rolls 267 N/V 270 Agree. The terms even and odd only apply to integers; 2.5 is neither even nor odd. Zero, on the other hand, is even since it is 2 times some integer: it's 2 times 0. To check whether a number is odd, see whether it's one more than some even number: 7 is odd since it's one more than 6, which is even. 273 In this case the answer is B, But the question might be xy/(y^2+y)<1, if so, then the answer is Littlefish’s answer E. 280 A kilowatt hour is the typical way that electricity is measured. “但兩城市的用電量一樣多”sounds like Y city also used k percent power from plant. Might be the question is asking “if both cities have same utility usage hours, what percent of power had Y city used?” In such question, we got (X*Hx)/(X*Hx+Y*Hy)= (XHx)/[XHx+(1/3)XHy] here Hx=Hy so, (XHx)/[(4/3)XHx]=3/4 this means x city used ¾ percent of power that x and y city combined. Hence, k=(3/4)*(k+y) Y=2/3 k. We choose A. But, does“有兩個單字”mean HP ( horse power耗電功率), or KW(kilowatt), or two vocabularies? If HP, then, weird. If KW, then P.
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