Exponential Growth and Decay Review

Select the functions that are exponential growth.

Select all the equations that represent exponential decay.

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

Suppose you deposit $3000 in a savings account that pays interest at an annual rate of 4%. What is the growth factor?

• 40

• 1.4

• 1.04

• 0.04

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(1.9)^x

• y=1400(.09)^x

What is the initial value for the function: f(x) = 300(1.16)^x?

• 300

• 1.16

• .16

• 16

A beetle population of 346,000 is too large to sustain. The beetles begin to perish at a rate of 8% per week. Write a function, f(x), for every x weeks.

• f(x) = 346,000(92)^x

• f(x) = 92(346,000)^x

• f(x) = 0.92(346,000)^x

• f(x) = 346,000(0.92)^x

• f(x) = 346,000(8)^x

The new Toyota Supra has a value of $50,000. Its value depreciates (decreases) by 1.3% every 6 months. Write a function, v, for its value for every x six-month periods.

• v = 0.87(50,000)^x

• v = 50,000(0.87)^x

• v = 50,000(1.3)^x

• v = 0.987(50,000)^x

• v = 50,000(0.987)^x

Given y = 89(0.75)^x , which statement is TRUE about the exponential function?

• The function is classified as exponential growth.

• The rate of decrease is 25%.

• The rate of increase is 75%.

• The initial value (a) is 0.75.

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