Name: ______________________
Class: _________________
Date: _________
ID: A
Exponential Decay and Growth Test Questions
1
y = a(1.09)
A
B
C
D
2
Exponential
Exponential
Exponential
Exponential
A
B
t
growth, 9%
growth, 81%
decay, 9%
decay, 81%
ˆ˜ t
˜˜
˜˜
˜¯
A
Exponential growth
Exponential decay
B
The value of a book is $258 and decreases at a
rate of 8% per year. Find the balue of the book
after 11 years.
A
B
C
D
4
The graph of which function is shown?
Identify the function as exponential growth or
decay.
ÊÁ 8
y = a ÁÁÁÁ
ÁË 5
3
5
Identify the function as exponential growth or
decay. Then find the rate of growth or decay as
a percent.
C
D
$56.98
$159.03
$101.38
$103.10
Write an exponential growth function to model
the situation given below to find the value of
the function after the given amount o time.
Membership of a local club grows at a rate of
7/8% yearly and currently has 30 members.
Find the membership after 6 years.
A
B
C
D
44
47
53
61
1
x
f(x) = 6
ÊÁ 1 ˆ˜ x
f(x) = ÁÁÁÁ ˜˜˜˜
ÁË 3 ˜¯
1
x
f(x) = • 6
3
ÊÁ 1 ˆ˜ x
f(x) = 6 • ÁÁÁÁ ˜˜˜˜
ÁË 3 ˜¯
Name: ______________________
6
7
ID: A
The graph of which function is shown?
x
A
y = (0.25)
B
y = (0.5)
C
y = 0.25 • (0.5)
D
y = 4 • (0.5)
x
x
x
In 2004 a person purchased a car for $25,000.
The value of the car decresed by 14% annually.
Describe and correct the error in writing a
function that models the value of the car since
2004. Justify your reasoning.
Error
t
y = a(1 − r)
= 25, 000(0.14)
t
2
ID: A
Exponential Decay and Growth Test Questions
Answer Section
1
2
3
4
5
6
7
ANS: B
ANS: A
ANS: D
ANS: B
ANS: C
ANS: D
ANS:
The error is that the
t
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
decay rate was placed where the decay factor should be. The equation should be:
t
y = a(1 − r) = 25, 000(1 − 0.14) = 25, 000(0.86)
t
PTS: 1
1