大家数学每做一道题都会验算一遍吗？/求助几道prep12

芊层酥

因为我觉得75min对于37道数学题而言是相对充裕的，然而自己每次prep都会因为粗心或者trap丢很多分= =
所以想问问大家平日做Q的节奏是怎样的？

另：求助几道prep12里的题
1. On a certain sight-seeing tour, the ration of the number of women to the number of children was 5 to 2. What was the number of men on the sight-seeing tour?
(1) The ratio of chirldren to men was 5 to 11
(2) The number of women was less than 30.
答案是C

2.What fraction of this year's graduating students at a certain college are males?
(1) Of this year's graduating students, 33 percent of the males and 20 percent of the females transferred from another college.
(2) Of this year's graduating students, 25 percent transferred from another college.
答案也是C。（我选的E……当时就觉得只知道25%转学来的有什么用，觉得B是完全废掉的）

3. For every positive even integer n, the function h(n) is defined to be th product of all the even integers from 2 to n, inclusive. If p is the smallest prime factor of h(100)+1, then p is
答案是 greater than 40. 这道题我一点思路都没有，完全不知道怎么入手……

4. Which of the following lists the number of points at which a circle can intersect a triangle?
答案是 1,2,3,4,5,6
这道题我题都没看懂= =

求各位大神解答TAT

sandrahuang

芊层酥 发表于 2015-8-18 21:27
太厉害了~~~明天就考了，现在两次prep都没上700，心情很复杂……看到你的解答坦然了好多~感谢TAT  ...

其实都差不多的，第二题我也傻乎乎的画了半天圈圈，发现把所有条件列下来原来最清晰。。

加油加油，明天好运~~~

芊层酥

sandrahuang 发表于 2015-8-18 21:08
1. On a certain sight-seeing tour, the ration of the number of women to the number of children was 5 ...

太厉害了~~~明天就考了，现在两次prep都没上700，心情很复杂……看到你的解答坦然了好多~感谢TAT

guanli_jun

哇，感谢楼上啊，我对第一题疑惑好长时间呢，原来是这样啊，哈哈。

sandrahuang

1. On a certain sight-seeing tour, the ration of the number of women to the number of children was 5 to 2. What was the number of men on the sight-seeing tour?
(1) The ratio of chirldren to men was 5 to 11
(2) The number of women was less than 30.

1+2， W：M=25：22， W<30, 那么只能W为25， M为22.  

2.What fraction of this year's graduating students at a certain college are males?
(1) Of this year's graduating students, 33 percent of the males and 20 percent of the females transferred from another college.
(2) Of this year's graduating students, 25 percent transferred from another college.

1+2：（33%男+20%女）/（男+女）=25%，可以求出男女的比例

3. For every positive even integer n, the function h(n) is defined to be th product of all the even integers from 2 to n, inclusive. If p is the smallest prime factor of h(100)+1, then p is

p=2x4x...x100+1 = 2^50 x(1x2x3x...x50)+1, 任何一个数m都不可能跟m+1有相同的factor（1除外），所以P不可能有1到50任何中的一个prime facter。

4. Which of the following lists the number of points at which a circle can intersect a triangle?
题目意思是：一个圆和一个三角形能有几个交点。