Compound interest The balance A (in dollars) in a saving account is given by A = 5000e0.08t,Where t is measured in years.Find the rates at which the balance is changing when (a) t = 1 year,and (c) t = 50 years.

Respuesta :

Answer:

a) [tex]\frac{dA}{dt}=400 e^{0.08(1)} =433.315[/tex]

b) [tex]\frac{dA}{dt}=400 e^{0.08(10)} =890.216[/tex]

c) [tex]\frac{dA}{dt}=400 e^{0.08(50)} =21839.260[/tex]

Step-by-step explanation:

For this case we have the following expression for the balance:

[tex] A = 5000 e^{0.08t}[/tex]

And we are interested on the rate at which the balance is changing for some values of t. The correct way to answer this is finding the derivate respect to t of A like this:

[tex]\frac{dA}{dt}= \frac{d}{dt} (5000 e^{0.08t})[/tex]

[tex]\frac{dA}{dt}= 5000 \frac{d}{dt}(e^{0.08t})[/tex]

[tex]\frac{dA}{dt}= 5000*0.08 e^{0.08t}[/tex]

[tex]\frac{dA}{dt}=400 e^{0.08t}[/tex]

So then we can solve for the different years like this

Part a

t= 1 years

[tex]\frac{dA}{dt}=400 e^{0.08(1)} =433.315[/tex]

So on this case would be $433.315 dollars per year

Part b

t=10 years

[tex]\frac{dA}{dt}=400 e^{0.08(10)} =890.216[/tex]

So on this case would be $890.216 dollars per year

Part c

t=50 years

[tex]\frac{dA}{dt}=400 e^{0.08(50)} =21839.260[/tex]

So on this case would be $21839.260 dollars per year