求神人解答几道GRE数学题1、A political poll showed that 80 percent of those polled said they would vote for proposition P.Of those who said they would vote for proposition P,70 percent actually voted for P,and of those who did not say they

求神人解答几道GRE数学题1、A political poll showed that 80 percent of those polled said they would vote for proposition P.Of those who said they would vote for proposition P,70 percent actually voted for P,and of those who did not say they
求神人解答几道GRE数学题
1、A political poll showed that 80 percent of those polled said they would vote for proposition P.Of those who said they would vote for proposition P,70 percent actually voted for P,and of those who did not say they would vote for P,20 percent actually voted for P.What percent of those polled voted for
(A) 56% (B) 60% (C) 64% (D) 76% (E) 90%
我列的算式是：0.8*0.7+0.2*0.2=60%,为什么答案是A呢?
2、
For the line with equation y=ax+b,ab≠0,the x-intercept is twice the y-intercept.
比大小：The slope of the line和0.5
Intercept到底要不要带正负号的啊?
3、
A rectangular floor with an area of 12 square meters is drawn to scale with 2 centimeters representing L meter.
比大小：The area of the scale drawing of the floor和24 square centimeters
4、2AF=AB=BD=DE=AE
比大小：The sum of the area of triangular region ABF and the area和The area of rectangular region BCEF
这个题目是不是错了啊?关于C的条件都没给出,图啊画不出来.
求具体算式啊!在此膜拜了!

求神人解答几道GRE数学题1、A political poll showed that 80 percent of those polled said they would vote for proposition P.Of those who said they would vote for proposition P,70 percent actually voted for P,and of those who did not say they
1.就应该是60%,答案错了
2.intercept表示截距,有符号,可以为负,所以应该选D（不确定）
3.原题是1meter不是Lmeter,题目意思是
一个长方形floor,面积12平方米,按比例,2厘米代表1米
则比较其面积与24cm²的大小
由比例尺1：50,则面积比例为1：50²=1：2500
则易得120000/2500=48>24
选A
4.你的题不完整
原题是
2AF=AB=BD=DE=AE,
A,The sum of the area of triangular region ABF and the area of triangular region CDE
B,The area of rectangular region BCEF'
由题中AB=BD=DE=AE可知 四边形ABDE为菱形,A,D位于线段BE的垂直平分线上
又BCEF为矩形（rectangular）
画图后得到,随菱形ABDE变化,矩形BCEF也在变化
有点儿复杂,我算一会再跟你说

第一题我也和lz一样的想法类...
第二题截距是带正负号的
第三题，应该是讨论L的大小在不断变化时，比例图的大小和24的关系吧
当两者相等的时候，有 24/12 =(2/L)^2(这里单位已经约过了)，L=√2
所以就√2作为零界进行讨论吧
第四题，其实是有隐藏条件的吧，ABDE很明显是菱形，BCEF是矩形，表明BE就是矩形的对角线，而C和F是矩形的另外两个...

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第一题我也和lz一样的想法类...
第二题截距是带正负号的
第三题，应该是讨论L的大小在不断变化时，比例图的大小和24的关系吧
当两者相等的时候，有 24/12 =(2/L)^2(这里单位已经约过了)，L=√2
所以就√2作为零界进行讨论吧
第四题，其实是有隐藏条件的吧，ABDE很明显是菱形，BCEF是矩形，表明BE就是矩形的对角线，而C和F是矩形的另外两个顶点，BC和EF垂直，矩形BCEF的面积就是两倍的三角形BFE的面积，所以题目就是三角形ABF和两倍三角形BEF的面积大小比较
只能做个参考啦...

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第一个答案错了吧。第二个正负，答案可以是相等的也可以是小于啊。。puzzled

a lot。。第三个48 square cm。大于号。2 cm equals 1 L meter，so we could assume the rectangular's size as 3m by 4m, in this way ,we could change the width to 3*2=6cm and the length same change to 4*2=8 cm,so the area of the scale drawing of the floor equals 6*8=48 square centimeters. 第四题我画了一个很有迷惑性的图。自己也糊涂了。。。。肯定错了