[求助]一道prep的数学题。。好绕

galamian

Of the 800 students at a certain college, 250 students live on campus and are more than 20 years old. How many of the 800 students live on campus and are 20 years old or less?
(1) 640 students at the college are more than 20 years old.
(2) 60 students at the college are 20 years old or less and live off campus.
 
答案是C 谢谢啊

galamian

额 还有一个问题请问p is the sum of the squares of two positive integers.  这句话的意思是不适两个整数平方的和就是a^2+b^2谢谢啦

galamian

自己顶 还有那个Of the 25 cars sold at a certain dealership yesterday, some had automatic transmission and some had antilock brakes. How many of the cars had automatic transmission but not antilock brakes?
(1) All of the cars that had antilock brakes also had automatic transmission.
(2) 2 of the cars had neither automatic transmission nor antilock brakes.
请问这题的All of the cars that had antilock brakes also had automatic transmission.是什么意思啊？？题目错了？？先谢谢

wj37044

1)800-640=160: 20 old or less

2)60: 20 old or less and off campus

=>160-60=100: 20 old or less and on campus

所以 c

galamian

可是 请问640 students at the college are more than 20 years old. 这句话的意思 640个人在学校大于20岁，那个800-640=160这些人是小于或等于20岁吗？？谢谢

linuxzh

   250      390
  --------------   
   100      60

   CAMP     OUTSIDE
 

cloudpacer

Of the 25 cars sold at a certain dealership yesterday, some had automatic transmission and some had antilock brakes. How many of the cars had automatic transmission but not antilock brakes?
(1) All of the cars that had antilock brakes also had automatic transmission.
(2) 2 of the cars had neither automatic transmission nor antilock brakes.

答案应该是E, (1) 没提数量, 肯定不行

             (2) 知道没有AB和AT的数量并不能知道有AT和没AB的数量.

联立1,2 也不行,

请问这题的All of the cars that had antilock brakes also had automatic transmission.是什么意思啊？？题目错了？？先谢谢

中文意思是  所有的有防抱死(ABS)刹车系统的车都是自动档的.   其实不懂英文没关系的, 只要缩写成 AB和AT就好了.