library fine - gmat prep question

[shivanimittal]

A certain library assesses fines fo roverdue books as follows. On the first day that a book is overdue, the total fine is $0.10. Fo reach 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 4th day it is overdue?

(i) $0.6
(ii) $0.7
(iii) $0.8
(iv) $0.9
(v) $1.00

I seem to be getting only 0.9 however i work it out. Am i understanding the question stem wrong?

[logitech]

A certain library assesses fines fo roverdue books as follows. On the first day that a book is overdue, the total fine is $0.10. Fo reach 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 4th day it is overdue?

(i) $0.6
(ii) $0.7
(iii) $0.8
(iv) $0.9
(v) $1.00

I seem to be getting only 0.9 however i work it out. Am i understanding the question stem wrong?

1st day

10

2nd day

40 > 20 ; so 20

3rd day

50 > 40 ; so 40

4th day

70 < 80 ; so 70

B

[iamcste]

First day fine=10

Second day fine= Min ( 40, 20)=20

Third day fine=Min(50,40)=40

Fourth day fine =Min (70,80)=70

hence 0.7


Your approach is

Second day fine= Min of Double of (0.1+0.3) or (01.+03)*2


hence you end up in 0.9 on fourth day

Key is to just consider fine of the previous day as the base and not the cumulative fine