LESSON Practice C 12-3 Exponential Growth and Decay

Name ________________________________________ Date __________________ Class__________________

LESSON Practice C

12-3 Exponential Growth and Decay

Write an exponential growth function to model each situation. Then find the value of the function after the given amount of time.

1. Annual sales for a furniture store are $375,000 and are increasing at a rate of 6.75% each year; 9 years

________________________________

___________________________

2. The population of Indiana showed an annual growth rate of

0.6% between 1998 and 1999. The population in 1999 was _______________________________

approximately 273,000,000. Based on this model, find the

population in 2007.

___________________________

3. Per capita income is the total income for a geographic area divided by the number of people in that area. In Florida, the per capita personal income (PCPI) of $30,098 is increasing at a rate of 3.6%; 8 years

___________________________ ___________________________

Write a compound interest function to model each situation. Then find the balance after the given number of years.

4. $60,000 invested at a rate of 2.5% compounded annually; 8 years

___________________________

5. $27,000 invested at a rate of 3.75% compounded quarterly; 3 years

___________________________ _________________________________

6. $95,000 invested at a rate of 4.2% compounded monthly; 10 years

___________________________ ________________________________

________________________________

Write an exponential decay function to model each situation. Then find the value of the function after the given amount of time.

7. The population of a town is 1800 and is decreasing at a rate of

3.8% per year; 6 years

___________________________

8. A population of 2300 manatees in Florida is thought to be decreasing at a rate of 1.1% annually; 7 years

___________________________ ___________________________

___________________________

9. The half-life of Cobalt-60 is approximately 5.25 days. Find the

amount of Cobalt-60 left from a 30 gram sample after 42 days.

Round to the nearest thousandth of a gram.

___________________________

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Holt McDougal Coordinate Algebra

5. x y 1 3 2 0 3 1 6 2 12

12-3 EXPONENTIAL GROWTH AND DECAY

Practice A

1. y 270,000(1 0.07)t; y $330,761.61

2. y 2200(1 0.02)t; y | 2478

3. y 200(1 0.08)t; y | $503.63

4. A

? 20,000 ??1

0.03 ? (1)(t) 1 ??

;

A | $25,335.40

5. A

? 35,000 ??1

0.06 ? (12)(t) 12 ??

;

A | $63,678.89

6. A

35,000

? ??1

0.08 ? 4t 4 ??

;

A | $52,008.16

7. y 800(1 0.02)t; y | 738

8. y 2300(1 0.04)t; y | 1529

9. A 10(0.5)t; A 2.5 grams

Practice B 1. y 650,000(1.04)x; |$790,824.39 2. y 800(1.02)x; |901 3. y 70(1.18)x; |136

4. y 50,000(1.0025)12t; |$59,847.42 5. y 43,000(1.05)t; |$49,777.88 6. y 65,000(1.015)4t; |$132,826.09 7. y 2500(0.97)x; |2147 8. y 25,000(0.85)x; |$6812.26

9. 2.1875 grams

Practice C 1. y 375,000(1.0675)x; |$675,059.76 2. y 273,000,000(1.006)x; |286,382,511 3. y 30,098(1.036)x; |$39,940.70 4. y 60,000(1.025)t; |$73,104.17 5. y 27,000(1.009375)4t; |$30,199.12 6. y 95,000(1.0035)12t; |$144,480.36 7. y 1800(0.962)x; |1427 8. y 2300(0.989)x; |$2129

9. |0.117 grams

Review for Mastery 1. y 372,000(1 0.05)t; |$549,613 2. y 4200(1.03)t; |5165 3. y 350,000(1 0.03)t; |$291,540 4. y 1200(0.98)t; |1085 5. A 17,000(1.03)t; $20,298.89

6. A

23,000

???1

0.02 4

?4t ??

;

$26,979.99

7. A = 30(0.5)t; 3.75 g 8. A = 40(0.5)t; 2.5 g

Challenge 1. A 10,000(1.0565)t

2.

t 0

1

2

3

A 10,000 10,565 11,161.92 11,792.57

4

5

6

7

12,458.85 13,162.78 13,906.47 14,692.19

3. a. sometime after the end of the third year but before the end of the fourth year

b. sometime after the end of the third year but before the end of the seventh year

4. 7.4 years

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Holt McDougal Coordinate Algebra

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