菜鸟问数学几道，虚心向nn们请教

xyzxf

1.A garden store purchased a number of shovels and a number of rakes. If the cost of each shovel was $14 and the cost of
each rake was $9, what was the total cost of the shovels and rakes purchased by the store?
(1) The ratio of the number of shovels to the number of rakes purchased by the store was 2 to 3.
(2) The total number of shovels and rakes purchased by the store was 50. 这题给的答案是C，但我做时B试值也只有1种结果，想知道B是不是可以

2.If n and m are positive integers, what is the remainder when 3^(4n + 2 + m) is divided by 10 ?
(1) n = 2 (2) m = 1

3.Six countries in a certain region sent a total of 75 representatives to an international congress, and no two countries sent the
same number of representatives. Of the six countries, if Country A sent the second greatest number of representatives, did
Country A send at least 10 representatives?
(1) One of the six countries sent 41 representatives to the congress.
(2) Country A sent fewer than 12 representatives to the congress

4.At least 100 students at a certain high school study Japanese. If 4 percent of the students at the school who study French
also study Japanese, do more students at the school study French than Japanese?
(1) 16 students at the school study both French and Japanese.
(2) 10 percent of the students at the school who study Japanese also study French.

5 When 1,000 children were inoculated with a certain vaccine, some developed inflammation at the site of the inoculation and
some developed fever. How many of the children developed inflammation but not fever?
(1) 880 children developed neither inflammation nor fever.
(2) 20 children developed fever.

6.During a sale, for each shirt that Mark purchased at the regular price, he also purchased a shirt at half the regular price.
How many shirts did Mark purchase during the sale?
(1) The regular price of each of the shirts that Mark purchased during the sale was $21.50.
(2) The total of the prices for all the shirts that Mark purchased during the sale was $129.00.

我心向明月

1.A garden store purchased a number of shovels and a number of rakes. If the cost of each shovel was $14 and the cost of
each rake was $9, what was the total cost of the shovels and rakes purchased by the store?

(1) The ratio of the number of shovels to the number of rakes purchased by the store was 2 to 3.
(2) The total number of shovels and rakes purchased by the store was 50. 这题给的答案是C，但我做时B试值也只有1种结果，想知道B是不是可以

B是指total number，不是total cost，B不成，先C。

我心向明月

2.If n and m are positive integers, what is the remainder when 3^(4n + 2 + m) is divided by 10 ?

(1) n = 2
(2) m = 1

3^1=3
3^2=9
3^3=27
3^4=81
3^5=729

当n=2时，3^(8+2+m)=3^(10+m)，没法确定；
当m=1时，3^(4n+2+1)=3^4n*3^3=81^n*27，可以确定，余数是7（因为81无论多少次方，个人都是1）

选B

我的数学完全还给老师了，用的办法比较原始，有没有比较快的办法？

我心向明月

5 When 1,000 children were inoculated with a certain vaccine, some developed inflammation at the site of the inoculation and
some developed fever. How many of the children developed inflammation but not fever?
(1) 880 children developed neither inflammation nor fever.
(2) 20 children developed fever.

1 单独得不出；
2 单独得不出；
1、2放在一起，也得不出
对不对呀？

我心向明月

6.During a sale, for each shirt that Mark purchased at the regular price, he also purchased a shirt at half the regular price.
How many shirts did Mark purchase during the sale?
(1) The regular price of each of the shirts that Mark purchased during the sale was $21.50.
(2) The total of the prices for all the shirts that Mark purchased during the sale was $129.00.

1 只给出了价格，无法得出数量；
2 假设原价x，数量为2y，2y*(x+0.5x)=129 -> xy=43，单独无法得出

1、2合在一起，x=21.50，则y=2，2y=4。

我心向明月

4. At least 100 students at a certain high school study Japanese. If 4 percent of the students at the school who study French
also study Japanese, do more students at the school study French than Japanese?

(1) 16 students at the school study both French and Japanese.
(2) 10 percent of the students at the school who study Japanese also study French.

条件1: 16/4%=400人，学法语的400人。
条件2：学日语的X，学法语的Y，则10%*X=4%*Y

条件2成立。

我心向明月

3. Six countries in a certain region sent a total of 75 representatives to an international congress, and no two countries sent the
same number of representatives. Of the six countries, if Country A sent the second greatest number of representatives, did
Country A send at least 10 representatives?

(1) One of the six countries sent 41 representatives to the congress.
(2) Country A sent fewer than 12 representatives to the congress

这个俺选E，算晕了，求指点。

xyzxf

谢谢，第5题答案是C，其他的你都是对的

月夜圣童

第五题是C，图解法：画两个相交的圆，一个表示F病一个表示i病，最外面画一个长方形表示总人数，相交圆有三个部分组成，只i病的只F病的和i，F病都有的，注意条件2说F病的人数是包含只F病的和i，F病都有的，所以由2个条件可得出只i病的

我心向明月

第五题是C，图解法：画两个相交的圆，一个表示F病一个表示i病，最外面画一个长方形表示总人数，相交圆有三个部分组成，只i病的只F病的和i，F病都有的，注意条件2说F病的人数是包含只F病的和i，F病都有的，所以由2个条件可得出只i病的

-- by 会员 月夜圣童 (2010/1/20 17:08:12)

谢谢月夜圣童，看到你要上考场了，祝你旗开得胜！