提问几道GRE数学!急!都是绿皮上的,本人数学不大好,请尽可能详细解释,谢谢!180.36If 2/3 of the number of women attending acertain dance is equal to 1/2 the number of men attending, what fraction ofthose attending are women?A.2

提问几道GRE数学!急!都是绿皮上的,本人数学不大好,请尽可能详细解释,谢谢!180.36If 2/3 of the number of women attending acertain dance is equal to 1/2 the number of men attending, what fraction ofthose attending are women?A.2
提问几道GRE数学!急!
都是绿皮上的,本人数学不大好,请尽可能详细解释,谢谢!
180.36
If 2/3 of the number of women attending a
certain dance is equal to 1/2 the number of men attending, what fraction of
those attending are women?
A.2/5 B.3/7 C.5/7 D.3/4 E.5/6
答案B 我算得2/7?
The length of a rectangular floor is 16
feet and its width is 12 feet. If each dimension were reduced by s feet to make
the ratio of length to width 3 to 2, what would be the value of s?
A0 B2 C4 D6 E8
答案C 没太读懂题且不会算
223.9
A board of length L feet is cut into two
pieces such that the length of one piece is 1 foot more than twice the length
of the other piece. What is the length, in feet, of the longer piece?
答案(2L+1)/3 咋算?
223.13
A watch gains 7 minutes and 6 seconds every
6 days. If the rate of gain is constant, how much does the watch gain in one
day?
答案是1min 11sec 我算得1min 1sec?
232.10
One-kth of a circular pie has been served.
If the rest of the pie is divided into n equal servings, then each of these servings
is what fraction of the whole pie?
答案(k-1)/nk 我算得1/nk^2?
191.18
If x^2=68, which of the following could be
true?
答案-9

提问几道GRE数学!急!都是绿皮上的,本人数学不大好,请尽可能详细解释,谢谢!180.36If 2/3 of the number of women attending acertain dance is equal to 1/2 the number of men attending, what fraction ofthose attending are women?A.2
设女的有x人,男的有y人,则2/3 * x = 1/2 * y,故4x=3y,即x=3/4 * y
从而女的比例为x/(x+y)=3/4 / (3/4+1)=3/7
长16宽12,都缩短s使得长宽比是3:2,故(16-s):(12-s)=3:2,求得s=6
设长的那块为x,则x=2(L-x)+1,求得x=(2L+1)/3
7分6秒=7*60+6=426秒,除以6,得71秒=1分11秒
总的为1,1/k去掉,还有(1-1/k),n等分,即为(1-1/k)/n=(k-1)/nk
x的平方是68,8的平方是64,9的平方是81,x的绝对值一定在8到9之间,所以8<x<9或-9<x<-8
x-5=2(15-x),得x=35/3

7a-5<=9,故a<=2；3-b>=2,故b<=1,a,b都是正数,所以ab的最大值应该为2*1=2,答案10应该不对

180.36
2/3 x = 1/2 * (1-x) => 7/6 x = 1/2 => x = 3/7
2. 矩形地面长16英尺宽12英尺，如果每边缩小S英尺以至于长宽比为3:2，S为何值？
将各选项代入，只有C成立， （16-4）：（12-4）=3:2
223.9 长的段为x，短的那段则为L-x。长的那段等于短的...

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180.36
2/3 x = 1/2 * (1-x) => 7/6 x = 1/2 => x = 3/7
2. 矩形地面长16英尺宽12英尺，如果每边缩小S英尺以至于长宽比为3:2，S为何值？
将各选项代入，只有C成立， （16-4）：（12-4）=3:2
223.9 长的段为x，短的那段则为L-x。长的那段等于短的的两倍加1：
x = （L-x）*2 +1 => x = (2L +1)/3
223.13
(7*60 + 6) / 6 = 71(秒）= 1分11秒
232.10 1/k的馅饼被吃掉，剩下1-1/k，再平均分成n份，每份占整个馅饼的：
（1-1/k) / n = (k-1)/ nk
191.18 x = 正的或负的根号68，是正或负8点几的一个数（比如说正的或负的8.2），所以可以是-9230.16 x是5到15之间的数字线上的数字，它到5的距离是到15的距离的两倍。
x-5 = 2*(15-x) => 3x = 35 => x = 35/3
265.7 7a-5 <=9 得出a <=2，a最大为2； 3-b>=-2 得出b <=5，b最大为5. ab最大为2*5=10

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