Question

2 NEW ! 英文数学问题 请数学高手帮帮我解答 >< 给十分 (不是要翻译 需要解答)

以下是我不会的英文数学问题 厉害的高手 请帮我解答一下问题 拜托了

1. The following table provided some information about the sex and level of the 80 students in a dance school.

Beginner , intermediate , advanced , total
Women ? ? ? 64
Man 4 8 4 16

One of the 80 students in this school is chosen at random, given that the student chosen is a women , the probability that she is at the intermediate level is 25%.
How many women in this dance school are at the intermediate level ?

2. A study of the 900 students in a school revealed the following information:
- There are 400 girls in this school.
- If one student is chosen at random , the probability that the student subscribes to the internet is 70%.
- If one student is chosen at random from among those who do not subscribe to the internet , the probability of choosing is 1/3 .

How many boys in this school are internet subscribe ?
(make a contingency table to solve)

请给我解答答案的过程 (算式) 还有问号 数字是什麼

Answer 1

1，由 given that the student chosen is a women 可以得知应从64个女生中选择，又因为占%25，所以应为16个
2，(不好意思，没算出来，不过你看一下式子有没有问题！）
subscribes to the internet是支持网络的意思
由题意
If one student is chosen at random , the probability that the student subscribes to the internet is 70%.
- If one student is chosen at random from among those who do not subscribe to the internet , the probability of choosing is 1/3 .
可知女生中支持网络的占总人数的70%，不支持的占总人数1/3
又知总人数为900 由此可列一个二元一次方程组 设总人数中支持的为x，不支持的为y（注意设的是总人数中！）

x+y=900，
x*70%+y*1/3=400
晕！没算出整数
不知咋回事，自己看看吧

则有 x+y=900

Answer 2

第一题 答案是12
第二题
第一问 350
第二问 200

Answer 3

题看懂了的话就很简单阿。
女生有64个 是intermidate的可能性是0.25 那就一共有16个female intermidate.

第二题不明确。student是男是女？