题目:of the 200 students at college T majoring in one or more of the sciences, 130 are majoring in chemistry and 150 majoring in biology. If at least 30 of the students are not majoring in either chemistry or biology, then the number students majoring in both biology and chemistry could be any number from
a) 20 to 50
b) 40 to 70
c) 50 to 130
d) 110 to 130
e) 110 to 150
问题:这道题能理解到是用集合的知识点,但是无论怎么做都无法突破,得到最后结果。还请老师讲解。谢谢
解答:
点赞0
阅读250842
解答:
sysadmin
提问:
调查1200人对A B C 的喜好,喜欢A的40%,喜欢B的58%,喜欢C的40%,同时喜欢AB的30%,求喜欢C但不喜欢A B的人
题目:A Printer numbered consecutively the pages of a book, beginning with 1 on the first page. In numbering the pages, he printed a total of 189 digits. How many pages are there in the book?
问题:看了中文翻译并听了管老师的讲解,我都没弄明白这个题目的解题思路。的别是对“a total of 189 digits”的处理。
题目:If n is a prime number greater than 3, what is the remainder when n的平方is divided by 12?
问题:当管老师解题时,他出了3个方程式,分别是:
1) n=3A+1, n的平方=9A(square)+6A+1
2) n=3A+2, n的平方=9A(square)+12A+4
3) n=2A+1, n的平方=4A(square)+4A+1
我不明白的点是:这3个方程式是怎么推到或者是一看到题目就这么设出来的?