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标题: 求助两道GMARPrep数学题, 因该很简单, 可是我做错了 [打印本页]

作者: liyan1688 时间: 2006-11-15 05:15
标题: 求助两道GMARPrep数学题, 因该很简单, 可是我做错了

If n and y are positive integer and 450y=n^3, which one must be integer?

A y/3x2^2 x5

B y/3^2x2x5

C y/3x2x5^2

答案是A, 不明白. 谁能帮忙解释一下?

A certain library assesses fines for overdue books as follows, on the first day that book is overdue ,the total fine is $0.10, for each dditional day that the book is overdue, the total fines either increased by $0.30 or doubled, whichever result in the lesser amount that is the total fine for a book on the fourth day it is overdue?

A.0.6

B 0.7

C 0.8

D 0.9

E 1.0

答案是B, 可是我怎么算都是0.8, 谁能提醒一下,我卡在哪里了? 谢谢!

作者: trecy 时间: 2006-11-15 05:41
the first one: 450 = 3^2*5^2*2,so y should be the multiple of 2^2*5*3.

作者: liyan1688 时间: 2006-11-15 11:52

哦, 明白啦, 谢谢你呀!!

作者: liyan1688 时间: 2006-11-15 21:15
请问谁知道第二道是怎么回事呀? 我算来算去还是$0.8

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