On 1st day:
Fine = $0.10

On 2nd day:
If doubled, then total fine = $0.20
If incremented, then total fine = $0.40

so total fine on 2nd day = $0.20

On 3rd day:
If doubled, then total fine = $0.40
If incremented, then total fine = $0.50

so total fine on 3rd day = $0.40

On 4th day:
If doubled, then total fine = $0.80
If incremented, then total fine = $0.70

so total fine on 4th day = $0.70

Choose B

-BM-

great elucidation BM !

The fine for one day: $0.1
The fine two days: $0.2, as it is less than $0.1+$0.3
The fine for three days: $0.4, as it is less than $0.2+$0.3
The fine for four days: $0.4+$0.3=$0.7, as it is less than $0.4*2
Answer is B

sanju09 wrote: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 double, whichever results in the lesser amount.

What is the total fine for a book on the fourth day it is overdue?

A $0.60
B $0.70
C $0.80
D $0.90
E $1.00

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 double, whichever results in the lesser amount.

What is the total fine for a book on the fourth day it is overdue?

A $0.60
B $0.70
C $0.80
D $0.90
E $1.00

Solution:

We need to determine the total amount of a fine for a book that is 4 days overdue. Let's determine each fine levied for when the book is overdue 1, 2, 3, or 4 days.

1 day overdue: $0.10

2 days overdue: The lesser of ($0.10 + $0.30 = $0.40) or (2 x $0.10 = $0.20)

Thus, the total fine for a book that is 2 days overdue is $0.20.

3 days overdue: The lesser of ($0.20 + $0.30 = $0.50) or (2 x $0.20 = $0.40)

Thus, the total fine for a book that is 3 days overdue is $0.40.

4 days overdue: The lesser of ($0.40 + $0.30 = $0.70) and (2 x $0.40 = $0.80)

Thus, the total fine for a book that is 4 days overdue is $0.70.

Note that the problem says the "total fine" is either increased by $0.30 or doubled. That is why, for each day's calculation, we didn't need to add the previous day's fine. If you don't read carefully, you might end up doubling the fine and adding it to the previous day's fine.

Answer: B