Select the Exponential Functions

Which of the following functions represents exponential DECAY? (Select ALL that apply)

• f(x) = 7(.54)^x

• f(x) = 7(1.20)^x

• f(x)= 500(3)^x

• f(x)= 2(.33)^x

Gasoline costs $1.99 per gallon. If the price per gallon increases an average of 6% per month, which function models the exponential growth of the pricing if t represents months.

• 1.06(1.99)^t

• 1.99(1.06)^t

• [1.06(1.99)]^t

• 1.99(.94)^t

Classify the model as Exponential GROWTH or DECAY.

A=1200(.85)x

• Growth

• Decay

Classify the model as Exponential GROWTH or DECAY.

A=10(1.01)^x

• Growth

• Decay

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

• y=5000(0.7)^x
• y=30(5000)^x
• y=5000(1.3)^x
• y=5000x^x

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

A beehive starts with 600 bees. The bee population grows at a rate of 4%. Which equation will allow you to figure out what the population is after 12 years?

• f(6)= 12

• f(x)=12(1.04)

• f(12)=600(1.04)¹²

• f(12)=12(1.04)⁶⁰⁰

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

What is the initial value in the exponential equation y = 25(.356)^x?

• 25

• 0

• .356

The expression 12(1.015)^t models the population of elephants in a wildlife refuge after t years since 1975.
Is the population of elephants increasing or decreasing?

• Increasing
• Decreasing