prep1有三题小迷茫，大家一定一定帮帮忙啊～

今天做了点数学～有以下三题不是很明白，大家帮忙解答一下啊～～非常感谢！！！

1.

If p is a prime number greater than 2, what is the value of p ?

(1)   There are a total of 100 prime numbers between 1 and p + 1.

(2)   There are a total of p prime numbers between 1 and 3,912.

选d, 我蒙的，不是很明白～～

2.

According to the directions on a can of frozen orange juice concentrate, 1 can of concentrate is to be mixed with 3 cans of water to make orange juice.  How many 12-ounce cans of the concentrate are required to prepare 200 6-ounce servings of orange juice?

(A)  25

(B)  34

(C)  50

(D)  67

(E)  100

选a, 我没的出答案啊～也许是我没看懂是怎么回事～我解不出答案！！

3.

Each of the students in a certain class received a single grade of P, F, or I.  What percent of the students in the class were females?

(1)  Of those who received a P, 40 percent were females.

(2)  Of those who received either an F or I, 80 percent were males.

这道题选e, 选c不行吗？？

大家一定要帮帮我啊！！万分感谢！！

我刚刚做完的一次模考，遇见了你这里的第三道

当然选E啦，因为没有告诉你P F I的比例是多少，所以你没法算出，收到P的grade中多少是女生

哦，对哈～谢谢了！！

以下是引用kingwin在2008-9-4 13:57:00的发言：

今天做了点数学～有以下三题不是很明白，大家帮忙解答一下啊～～非常感谢！！！

1.

If p is a prime number greater than 2, what is the value of p ?

 

 

(1)   There are a total of 100 prime numbers between 1 and p + 1.

 

 

(2)   There are a total of p prime numbers between 1 and 3,912.

选d, 我蒙的，不是很明白～～

2.

According to the directions on a can of frozen orange juice concentrate, 1 can of concentrate is to be mixed with 3 cans of water to make orange juice.  How many 12-ounce cans of the concentrate are required to prepare 200 6-ounce servings of orange juice?

 

 

(A)  25

(B)  34

(C)  50

(D)  67

(E)  100

选a, 我没的出答案啊～也许是我没看懂是怎么回事～我解不出答案！！

3.

Each of the students in a certain class received a single grade of P, F, or I.  What percent of the students in the class were females?

 

 

(1)  Of those who received a P, 40 percent were females.

 

 

(2)  Of those who received either an F or I, 80 percent were males.

这道题选e, 选c不行吗？？

大家一定要帮帮我啊！！万分感谢！！

1.

a)p跟1之間共有100個質數 , p位置固定 正確!

b)3912跟1之間的質數個數固定 正確!

得d

2.水:濃縮橘子果汁=3:1

現在問需要多少12 ounce 1can的果汁 做成200份 6 ounce的混合果汁

200x6 =1200 ounce  , 水跟濃果汁3:1 =>水要900 濃果汁要300 ounce

300 / 12 =25  can

对于第一题，还是有点不太明了，就是题目中说p是质数，那么第二个条件在1-3912的质数数目是p，能保证这个p也是质数个吗？？

第二题没看清，我以为是2006盎司了～～

谢谢ls战友，不过能否再解释一下第二道～～

第一题～谁能再来解释一下啊？？？快来说说吧～战友们战友们！！