作业帮提问几道GRE数学!急!
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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
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
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
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