Exponential Models

Suppose a culture of bacteria begins with 5000 cells and dies by 30% each year. Write an equation that represents this situation.

• y=5000(1 - 0.30)^x

• y=30(5000)^x

• y=5000(1 + 0.30)^x

• y=5000x^x

Tags

CCSS.HSA.CED.A.1

CCSS.HSF.BF.A.1

CCSS.HSF.LE.A.1

CCSS.HSF.LE.A.2

CCSS.HSF.LE.B.5

The value of a car is $15,000 and depreciates at a rate of 8% per year. What is the decay factor?

• ^.08
• ^1.08
• .92
• 8

Tags

CCSS.HSF.LE.A.1

CCSS.HSF.LE.A.2

CCSS.HSF.LE.B.5

The original value of a painting is $1400, and the value increases by 9% each year. Write an exponential growth function to model this situation.

• y=1400(1.09)^x
• y=1.09(1400)^x
• y=1400(.91)^x
• y=1.09^x

Tags

CCSS.HSA.CED.A.1

CCSS.HSF.BF.A.1

CCSS.HSF.LE.A.1

CCSS.HSF.LE.A.2

CCSS.HSF.LE.B.5

A population of fish starts at 8,000 and decreases by 6% per year. What is the population of fish after 10 years?

• 14327
• 4309
• 839
• 7680

Tags

CCSS.HSA.CED.A.1

CCSS.HSF.BF.A.1

CCSS.HSF.LE.A.1

CCSS.HSF.LE.A.2

CCSS.HSF.LE.B.5

Which of the following functions shows an initial amount of $15 and an increase of 35% each year?

• y = 15(35)^x
• y = 15(1.35)^x
• y = 15(0.35)^x
• y = 35(1.15)^x

Tags

CCSS.HSF.LE.A.2

The amount of ants in a colony, f, that is decaying can be modeled by

f(x) = 800(.87)^x, where x is the number of days since the decay started.

Suppose f(20) = 49. Which of the following is true?

• After 20 days, there are 49 ants in the colony.

• After 49 days there are 20 ants in the colony.

• The amount of ants times 20 is 49.

• After 20 days the amount of ants remaining decreases by 49.

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.SSE.A.1

CCSS.HSF.IF.A.1

CCSS.HSF.IF.A.2

CCSS.HSF.LE.A.1

The expression 12(1.015)^t models the population of elephants in a wildlife refuge after t years since 1975.
What does the value 1.015 represent?

• The number of elephants was 1,015 in 1975.
• The number of elephants increases by 1.5% each year.
• The number of elephants increases by 101.5% each year.
• The number of elephants is multiplied by 1.015 each year.

Tags

CCSS.HSA.SSE.A.1

James' 70 in. giant peach doubles in size every week. Write an expression that would represent how big the peach is after 5 weeks.

• 70(2)³⁵

• 70(2)⁵

• 2(70)⁵

• 5(70)²

Tags

CCSS.HSA.SSE.A.1

CCSS.HSF.BF.A.1

CCSS.HSF.BF.A.2

CCSS.HSF.IF.B.4

CCSS.HSF.LE.A.1

CCSS.HSF.LE.A.2

The number of mosquitoes at the beginning of the summer was 4,000. The population of mosquitoes is expected to grow at a rate of 25% a month. How many mosquitoes will there be after 4 months?

• 9766
• 9006
• 9765
• 5433

Tags

CCSS.HSF.BF.A.2