Question

A copier reduces an image in area by 5% each time it is copied. Marta copies repeatedly an image with an area of 90 square inches. Which of these can be used to determine the area of the image after it is copied
n
times?


f
(
n
)
=
90
(
0
.
95
)
n


f
(
n
)
=
90
(
0
.
05
)
n


f
(
n
)
=
90
−
0
.
05
n


f
(
n
)
=
90
(
0
.
95
)
n

Answer 1

Each copy keeps 95% of the area, so multiply by 0.95 each time. The area after n copies is

f(n) = 90(0.95)^n.