一道郁闷的Prep ....

kittycd

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

答案是$0.70. 我多给人家算了,$0.80....

多谢！！！！

dongstar

第一天0.1
第二天：如果+0.3=04.如果doubled就是0.2。后者要少些，所以doubled。。0.2

第三天：如果+0.3=0.5.如果doubled是0.4。后者少，所以0.4
第四天：如果+0.3=0.7，如果doubled是0.8.前者少。所以是0.7

georgina1107

我搜到了别人的回答

king12wolf
“题目说第一天是0.1  第二天开始要么比前一天多0.3  要么double   然后选低的那个  所以第一天0.1  第二天0.2 第三天 0.4 第四天0.7 ”

jack3939889

“First day   0.1

second day    0.1+0.3   OR   0.1*2

third day   (0.1+0.3)+0.3  or  (0.1+0.3)*2  OR (0.1*2)+0.3   or (0.1*2)*2  

4th  0.7*2 or 0.7+0.3  or 0.8*2  or 0.8+0.3   or  0.5*2 or 0.5+0.3 or 0.4*2  or 0.4+0.3=0.7(People will choose the smallest fine) ”

georgina1107

楼上的思路也清楚得很啊，谢谢
我发现我看题还是有点问题

kittycd

多谢好人！！！！！！