Exponential Growth and Decay

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

• 300

• 1.16

• .16

• x

Is the equation y = 4(0.20)^x modeling exponential growth or decay?

• Growth

• Decay

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

An antibiotic is introduced into a colony of 12,000 bacteria during a laboratory experiment. The colony is decreasing by 14.9% per minute. Which function can be used to model the number of bacteria in the colony after x minutes?

• f(x) = 12000(1 + 14.9)^x

• f(x) = 12000(1 - 14.9)^x

• f(x) = 12000(1 + 0.149)^x

• f(x) = 12000(1 - 0.149)^x

Twenty years ago, Mr. Davis purchased his home for $160,000. Since then, the value of the home has increased about 5% per year. How much is the home worth today?

• $176,783.29

• $424,527.63

• $57,357.75

• $532,041,076.80

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

Moody's Print Shop purchased a new printer for $35,000. Each year its value depreciates at a rate of 5%. How much will the printer be worth in 8 years?

• $23,219.72

• $136.72

• $51,710.94

• $16,710.94