The value of a car can be modeled by the equation y = 24,000(0.845)t where t is the number of

years since the car was purchased.

a. After how many years will the value of the car be $10,000?


b. Use the model to predict the value of the car after 50 years. Is this a reasonable value?

Explain.

Answer :

Answer: 5.2 years, $5.28

Step-by-step explanation:

Given

The value of a car is given by [tex]y=24,000\left(0.845\rght)^t[/tex]

Substitute  [tex]\$10,000[/tex] for [tex]y[/tex]

[tex]\Rightarrow 10,000=24,000\left(0.845\right)^t\\\\\Rightarrow \left(0.845\right)^t=\dfrac{5}{12}\\\\\Rightarrow \left(0.845\right)^t=0.41666\\\text{Taking log both sides}\\\Rightarrow t\ln (0.845)=\ln (0.4166)\\\\\Rightarrow t=\dfrac{\ln 0.4167}{\ln 0.845}\\\\\Rightarrow t=5.197\approx 5.2\ \text{years}[/tex]

(b) After 50 years, it is

[tex]\Rightarrow y=24,000\left(0.845\rght)^{50}[/tex]

[tex]\Rightarrow y=24,000\times 0.00022\\\Rightarrow y=\$5.28[/tex]

No, this is not a reasonable value as it is more than 4000 times less.

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