Exponential Growth and Decay Percentages

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

• 9760

• 5433

What type of function is f(x)=2(1/7)^x ?

• Exponential Growth

• Linear

• Exponential Decay

• None of the Abovee

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

Write an equation that models the following situation:
Samantha's hair was known to grow very rapidly. It began at a length of 6 in and grew at a rate of 14% a week.

• y=6(0.14)^x

• y=6(1+14)^x

• y=6(1.14)^x

• y=6(0.86)^x

Determine if the function is increasing or decreasing. Then, tell the rate by which the function is increasing or decreasing by.

Select all that apply.

• Increasing

• Decreasing

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. By what percentage is the colony decaying?

• 87%

• 13%

• 800%

• 8.7%

Which of the following could be represented by A=200(1.1)^t

• I started with $200 and lost 1% per week

• I started with $200 and lost 10% per week

• I started with $200 and gained 1% per week

• I started with $200 and gained 10% per week

A radioactive substance decays at a rate of 5% per year. If the initial amount of the substance was 100 grams, how much will remain after 20 years?

• 35.85 grams

• 37.69 grams

• 40.10 grams

• 42.58 grams

• Exponential Growth

• Linear

• Exponential Decay

• None of the Abovee