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Acad. Algebra 2
Graded Assignment
Name______________________________
Identify each of the following as exponential growth or decay. State the growth or decay
factor. Also state the percent of increase or decrease. (3 pts each)
1.)
y = 72(1.6)x
2.)
y = 0.9(0.92)x
For each of the following, answer the question using the compound interest formula, and
then determine the effective APY. State your answers using complete sentences. (4 pts
each)
3.) $1000 is deposited into an account which earns 5% annual interest compounded
monthly. What is the account value after 15 years?
4.) $2500 is deposited into an account which earns 6.25% annual interest compounded
quarterly. What is the account value after 35 years?
For each of the following, write an exponential function to represent the problem
situation, and state what each variable represents. Then answer the question. Show all
work and state the answer to the question in complete sentences. (5 pts each)
5.) A $12,000 car depreciates 25% each year. What is the car’s value 5 years later?
6.) A population of 2785 brown bears increases 3% each year. What is the population of
the brown bears 40 years later?
For each of the following, write an exponential function to represent the problem
situation, and state what each variable represents. Then answer the question. Show all
work and state the answer to the question in complete sentences. (5 pts each)
7.) 50 mg of I-123, which may be used for thyroid scans, has a half-life of 13 hours. How
much of the substance is remaining 48 hours later?
8.) You have one gram of a mixture that is losing 1% of its mass each hour by
evaporation. How much is remaining exactly 1 day later?
For each of the following, write an exponential function to represent the problem
situation, and state what each variable represents. Then answer the questions. Show all
work and state the answer to the questions in complete sentences. (6 pts each)
9.) The mass of a radioactive element is 3 mg and 10 years later is 2.85 mg.
a.) What is the decay factor?
b.) What is the annual rate of decrease?
10.) In a city, in January 2001, 15 people had been infected with an incurable disease. In
July 2001, 38 people had the disease.
a.) What is the growth factor?
b.) What is the monthly rate of increase?
c.) How many people will have the disease by January 2003?