求助数学，先谢了！！！

好好备考Gmat

1.If the prime numbers p and t are the only prime factors of the integer m, is m a multiple of p²t ?



(1) m has more than 9 positive factors.



(2) m is a multiple of p³.

【答案】B
2。A certain group of car dealerships agreed to donate x dollars to a Red Cross chapter for each car sold during a 30-day period.What was the total amount that was expected to be donated?



(1)A total of 500 cars were expected to be sold.



(2)60 more cars were sold than expected, so that the total amount actually donated was $28,000.

正确答案：c
我选A，每台车捐30，卖了500台，总数不是很清楚吗？为啥还加条件呢？还是我对问题的理解有误？
3.
If K is a positive three-digit integer, what is the hundreds digit of K ?



(1)The hundreds digit of K + 150 is 4.



(2)The tens digit of K + 25 is 7.

这种题我是没头绪的，见过不止一次了,我选e,因为我不知道怎么解
答案e

4
Juan bought some paperback books that cost $8 each and some hardcover books that cost $25 each.If Juan bought more than10 paperback books, how many hardcover books did he buy?



(1)The total cost of the hardcover books that Juan bought was at least $150.



(2)The total cost of all the books that Juan bought was less than $260.
答案c   我选e





2。A certain group of car dealerships agreed to donate x dollars to a Red Cross chapter for each car sold during a 30-day period.What was the total amount that was expected to be donated?



(1)A total of 500 cars were expected to be sold.



(2)60 more cars were sold than expected, so that the total amount actually donated was $28,000.

正确答案：c
我选A，每台车捐30，卖了500台，总数不是很清楚吗？为啥还加条件呢？还是我对问题的理解有误？
3.
If K is a positive three-digit integer, what is the hundreds digit of K ?



(1)The hundreds digit of K + 150 is 4.



(2)The tens digit of K + 25 is 7.

这种题我是没头绪的，见过不止一次了,我选e,因为我不知道怎么解
答案e

4
Juan bought some paperback books that cost $8 each and some hardcover books that cost $25 each.If Juan bought more than10 paperback books, how many hardcover books did he buy?



(1)The total cost of the hardcover books that Juan bought was at least $150.



(2)The total cost of all the books that Juan bought was less than $260.
答案c   我选e

好好备考Gmat

没人理，自己顶

wwhappy

第一题：有可能m的factor是1,p,t,pt,pt^2,pt^3,pt^4,m...即使多余9但就是没有p^2的factor，所以条件（1）推不出；由条件（2）可知m中一定有p^2t这个factior所以答案为B!

第二题我也没理解，对题目理解有误!

第三题只要LZ列一个竖式进行加法运算就可以很快的得出答案了！

第四题我说一下答案C吧，8p+25h<260(注意没有等号)且p>10,25h>=150,综合这么多条件我们只能得出25h=150,p=11！
不知有没有说清楚，表达能力有限！！！

Wgy888

第二题意思是说：在30天的期限内，每卖出一辆捐x元吧。

wwhappy

第二题：
1) Total of 500 cars sold. Fine! But, we don’t know x, so donation amount cannot be computed. (Not Sufficient)
2) Let N be total number of cars: (N + 60)X = 28000
Again we don’t have N and X – Not Sufficient

Combine 1) and 2)
560 * X = 28000
X = 2800 / 56 = 50

Total Contribution = 25000

好好备考Gmat

thanks

maningmz

第一题，p,t 都是m的质因数，问m是不是p^2t的倍数，其实就是问m里面是否有至少2个p，所以对于A选项，就算有9个因数，也不说明就一定有2个p啊，同理，B选项说有3个p就是对的了。。。

第二题，What was the total amount that was expected to be donated？就是问本来期望捐多少钱？在DS里，如果问了what，how many等词，就必须得出具体数字，像50X这种答案是不行的。。。同样，要是问了is。。。？就一定要回答出yes或者no。。。

第三题，题目说k是一个三位数，那么假设k的百十个位分别为a，b，c，所以k看上去就是abc
1号条件， abc
              +150
              ———
         4XX（X就是指叉叉，无意义）
假如b+5>=10那么a=2
假如b+5<10那么a=3
无法确定
2号条件单独根本无意义
1+2号条件
        abc
            + 25
           ————
        X7X
假如c+5>=10那么b=4
假如c+5<10那么b=5
将b=4带入1号条件的假设处，那么a=3
将b=5带入1号条件的假设处，那么a=2
所以无法确定，选e

第四题，应该能看出本题不选A,B的
看下C
题目有P>10,所以P至少等于11，所以8p至少等于88
考虑
25h>=150
8p+25h<260
举例子：
8本p加上6本h
88+150=238<260,符合
8本p加7本h
88+175=263>263，不符合
所以唯一解，h=6

表达的不好，请担待。。。

好好备考Gmat

多谢多谢

lastjuly

第二题：
1) Total of 500 cars sold. Fine! But, we don’t know x, so donation amount cannot be computed. (Not Sufficient)
2) Let N be total number of cars: (N + 60)X = 28000
Again we don’t have N and X – Not Sufficient

Combine 1) and 2)
560 * X = 28000
X = 2800 / 56 = 50

Total Contribution = 25000

-- by 会员 wwhappy (2010/8/5 23:06:25)

THX~