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标题: 求PREP-PS-2-193 思路 [打印本页]

作者: 小娟子NUNU 时间: 2010-5-16 10:37 标题: 求PREP-PS-2-193 思路

193.
In a class of 30 students, 2 students did not borrow any books from the library, 12 students each borrowed 1 book, 10 students each borrowed 2 books, and the rest of the students each borrowed at least 3 books. If the average (arithmetic mean) number of books borrowed per student was 2, what is the maximum number of books that any single student could have borrowed?

(A) 3

(B) 5

(C) 8

(D) 13

(E) 15

求思路....

谢谢

作者: besttys 时间: 2010-5-16 21:29

是不是选D?

作者: xingzixin 时间: 2010-5-17 06:41

共有30*2=60本书，
其中：2个人没有借书
12个人：12*1=12本书；
10个人：10*2=20本书；
此时共剩30-2-12-10=6个人，分剩下的60-12-20=28本书
又剩下6人每人至少借三本书，所以其中5个人均借了最少的3本书时，第6个人借书最多为28-5*3=13本书

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