A quantity with an initial value of 8500 decays exponentially at a rate such that the

quantity cuts in half every 5 decades. What is the value of the quantity after 97 years,

to the nearest hundredth?

Respuesta :

Answer:

[tex] 4250 = 8500 e^{50 k}[/tex]

And we can divide both sides by 8500 and we got:

[tex] \frac{1}{2} = e^{50 k}[/tex]

And we can solve for k using natural log

[tex] k = \frac{ln(\frac{1}{2})}{50}= -0.0138629[/tex]

And we have the model give by:

[tex] P(t) = 8500 e^{-0.01386294361 t}[/tex]

And if we replace t =97 we got:

[tex] P(t=97) = 8500 e^{-0.01386294361 *97}= 2215.240[/tex]

Step-by-step explanation:

For this case we can use the proportional model given by:

[tex]\frac{dP}{dt}= kP[/tex]

And we can rewrite the expression like this:

[tex] \frac{dP}{P} = k dt[/tex]

If we integrate both sides we got:

[tex] ln P = kt +C[/tex]

If we apply exponentials in both sides we got:

[tex] P = e^{kt +C}[/tex]

And we can rewrite the expression like this:

[tex] P(t) = P_o e^{kt}[/tex]

Where P represent the population and t the time in years since the starting value

For this case we have that [tex] P_o = 8500[/tex]

And after t = 5*10 = 50 years the value is the half or 8500/2 = 4250

So we can use this condition and we have:

[tex] 4250 = 8500 e^{50 k}[/tex]

And we can divide both sides by 8500 and we got:

[tex] \frac{1}{2} = e^{50 k}[/tex]

And we can solve for k using natural log

[tex] k = \frac{ln(\frac{1}{2})}{50}= -0.0138629[/tex]

And we have the model given by:

[tex] P(t) = 8500 e^{-0.01386294361 t}[/tex]

And if we replace t =97 we got:

[tex] P(t=97) = 8500 e^{-0.01386294361 *97}= 2215.240[/tex]