The function f(n) = 1.5 + 0.5(n −1)
�
(
�
)
=
1.5
+
0.5
(
�
−
1
)
models a book fine, in dollars, that a library charges for a book that is n days overdue.
What is overdue for a library book defined by the function f(10−3)
�
(
10
−
3
)
?
Responses
$4.50
$4.50
$6.50
$6.50
$5
$5
$3
The answer is $5.
To see why, we need to plug in 10−3 for n in the function f(n) and simplify:
f(10−3) = 1.5 + 0.5(10−3 − 1)
= 1.5 + 0.5(9−3)
= 1.5 + 0.5(6)
= 1.5 + 3
= 4.5
Therefore, the overdue fee for a book that is 10−3 days late is $4.50.