Exponential Decay Quick Check

You buy a car for $4800. The car depreciation rate is 14.7% annually. Which equation models how much the car would be worth after t years?

•  $y=4800\left(0.147\right)^t$  

•  $y=4800\left(0.0147\right)^t$  

•  $y=4800\left(0.853\right)^t$  

•  $y=4800\left(1.147\right)^t$  

A 78 gram sample of Uranium loses half of its mass each year.  How much is left after 6 years?

• 13 grams
• 6.5 grams
• 1.22 grams
• 592.31 grams

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

Give the rate of decay:
y = 35(0.65)^x

• 35%
• 65%
• .35%
• 165%

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

Daniel’s Print Shop purchased a new printer for $35,000. Each year it 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

Which of the following models represents exponential decay?

• y = 5(1 + .05)^t

• y = 5(1 - .05)^t

• y = .8(1 + .05)^t

• y = -2(1 + .05)^t

Which of the following is an example of exponential decay?

• y = 8(.5)^x

• y = .8(5)^x

• y = 8(5)^x

• y = 8(2)^x

Esther purchased a used car, a Ford Focus, for $8400. The car is expected to decrease in value by 20% per year over the next couple of years. What would be the decay factor?

• 80

• 20

• 0.20

• 0.80

A bicycle depreciates at a rate of 15%. Therese bought a bicycle for $250. How much should it be worth 6 years later?

• $225.00

• $123.74

• $94.29

• $578.27