1.
Radioactivity
The half-life of uranium-232 is 72 years. Find the approximate value of
k
in the formula
y
=
ne
kt
for uranium-232. Assume
t
is in years.
A.
0.0012
B.
-0.0024
C.
-0.0048
D.
-0.0096
Hint
2.
Population
The population of Redville grew from 5432 in 1990 to 7116 in 2000. Assuming the population is growing exponentially, predict the population of Redville in 2005.
A.
about 7960
B.
about 8290
C.
about 8140
D.
about 8360
Hint
3.
A Mickey Mantle rookie card appreciates in value 2% every year. If it is worth $35,000 in 2000, when will it be worth $100,000?
A.
2065
B.
2093
C.
2043
D.
2053
Hint
4.
Two cities have insect problems. The insects in City A increase exponentially according to the equation
y
= 120,000
e
0.04
t
. The insects in City B increase exponentially according to the equation
y
= 90,000
e
0.08
t
. When will the cities have an equal amount of insects?
A.
at
t
= 7.19 years
B.
at
t
= 7.89 years
C.
at
t
= 3 years
D.
at
t
= 34.66 years
Hint
5.
Suppose a new car loses value at 10% per year for the first 5 years. When should the owner sell it if they want to receive 75% of what they paid for it?
A.
after 3 years
B.
after 2 years
C.
after 2.73 years
D.
after 2.5 years
Hint