prep ds1-45

45.        3906-!-item-!-187;#058&003579

How many of the 42 people in a group are employed students?

(1)  29 of the 42 people are employed.

(2)  24 of the 42 people are students.

这道题从集合角度来说非常简单的，就是有点糊涂的是，之所以选e,是不是因为对42的合集(如果还有non-student , non-employment， 42就是合集，否则就是总集）给出的定义不明确? 我有点不明白gmac到底怎么定义合集的，比如 ds-1-37

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?C

(1)  880 children developed neither inflammation nor fever.

(2)  20 children developed fever

选C，总集是1000， inflammation和fever的合集是1000-880 ，但是对于20个fever的，根据答案应该是包括了inflammation和fever的交集，但是为什么呢？

谢谢解释！

45.  29 of 42 employed 推出13 of 42 unemployed; 24 of 42 student,推出18 of 42 non-student; 但是这些信息加起来推不出有多少是employed student，因为24个学生可以任意分布。

37.  1000个chidren得病，880没得Inflammation也没得fever,那么有120个至少得了i和f中的一种(或者都得了);这120中，有20个得了fever(包括都得的)，那么剩下100个只得了Inflammation而没得fever，所以(1)+(2)充分。