单选题In a class of 160 seniors, the ratio of boys to girls is 3 to 5. In the junior class, the ratio of boys to girls is 3 to 2. When the two classes are combined, the ratio of boys to girls is 1 to 1. How many students are in the junior class?A 400B 360C 2

题目
单选题
In a class of 160 seniors, the ratio of boys to girls is 3 to 5. In the junior class, the ratio of boys to girls is 3 to 2. When the two classes are combined, the ratio of boys to girls is 1 to 1. How many students are in the junior class?
A

400

B

360

C

200

D

180

E

160

参考答案和解析
正确答案: C
解析:
因为这个班共有160人,男生和女生的比例为3:5,所以男生和女生的人数分别为(3/8) ×160 = 60人,(5/8) ×160 = 100人。假设另一班男生女生人数共有x人,那么男生女生的人数分别为(3/5)x,(2/5)x,又因为当两班的人数相加后,男生女生的比例相等,所以可得出60 + (3/5)x = 100 + (2/5)x,经计算,x = 200。
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相似问题和答案

第1题:

B

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People found that girl chimps in Tanzania,East Africa,use sticks to find tasty insects(昆虫) two years earlier than boy chimps. This is because young girl chimps watch their moms col-lect bugs,while the boy chimps climb trees.

But young boy chimps may hunt and throw(扔) sooner than girl clumps.It's also true for humans.It-s easier for girls to learn to write and draw earlier,but boys often run and throw balls earlier than girls.

Teacher's view:l think boys and girls both have their special advantages. Boys are good at sports. They are very athletic. But girls do well in performance. They are very calm.

( )26. People usually think boys are _________'than girls.

A. taller

B. stronger

C. heavier

D. All of the above


正确答案:D
26.D【解析】由第一段第一句话可知.

第2题:

30. What-s the best title of the passage?

A. Boys and Girls. .

B. Are’Girls Smarter?

C. Young Boy and Girl Chimps.

D. Are Boys Slower?


正确答案:B
30.B【解析】全文围绕专家不同意女孩没有男孩聪明这个观点提出事实论据,故选B.

第3题:

Bob is __ of the two boys. Mary is ____ of the three girls.

A、tall,short

B、taller,the shorter

C、tallest,the shortest

D、the taller,the shortest


参考答案:D

第4题:

In terms of receiving acceptance from teachers the proportion of boys to girls is appropriately equal. (Sexism in Class) ()

此题为判断题(对,错)。


正确答案:T

第5题:

According to the author, the reason why parental divorce has greater effect on boys than on girls is that_____.

[A] all cultures encourage male aggression and noncompliance

[B] boys are always involved in their parents’ fights

[C] males are usually viewed as the models in self-control and strong will

[D] boys are basically more self-disciplined than girls


正确答案:C

本题考查推理引申。第三段中间作者提出了一个问题,怎样解释离婚对男孩影响比女孩大的原因呢?接下来文章从三个方面进行了解释:一,我们的文化更能容忍男孩具有攻击性和不驯服;二,男孩更希望树立起自律的强悍的男人形象,也希望父母严格自律;三,男孩较少受到他人的同情与支持。[C]符合第二点原因,是正确项。[A]错在“所有文化”,文章中是“我们的文化”。[B]错在“卷入(involved in)”,全文最后一句提到的是“男孩更容易看到(be exposed to)父母吵架”。[D]这种说法无从推知。

第6题:

28. Teachers think that__________

A. boys and girls both have their special advantages

B. boys are calmer than girls

C. girls are better at sports than boys

D. girls do better in drawing than boys


正确答案:A
28.A【解析】由最后一段第一句话可知.

第7题:

Boys like sports more than girls, they are very _a __________.


正确答案:
35. athletic

第8题:

Class one has 23 _________.()

A.boy students

B.boys students

C.boy’s students

D.students of boys


参考答案:A

第9题:

The text indicates that private schools are very selective because they

[A] have no reliable methods to pick students for a class.

[B] want a good mixture of boys and girls for classes.

[C] encounter more demand than they can cope with.

[D] prefer to enroll children of their relatives.


正确答案:C
43.C该题为推理题。根据第三段“The problem for the applicants is that while demand has increased.supply has not.”可知申请私立学校的人数在增加,但私立学校的招生名额却没有增加。接着第四段详细讲了一些私立学校如何选择学生。由此可推断,私立学校对学生如此精挑细选的原因在于有太多的学生申请,他们不得不通过各种方法来选择学生。选项A与文章的意思有所出入,第四段第二句“Schools know there is no easy way to pick a class when children are so young.”可知学校认为选择学生没有简单的方法,并不是如A项所表示的选择的方法不可靠。选项B是某些学校选择生源的方法,即男女比例协调,由此可知A、B两项不能作为学校精心选择学生的原因。选项D在文中没有提及,故选C。

第10题:

Girls are usually a little weaker than boys __________ mathematics.

A、at

B、 in

C、with

D、as to


参考答案:B

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