Wednesday, October 28, 2009

Calculus help please!!!! Compound Interest?

4000 dollars is invested in a bank account at an interest rate of 8 per cent per year, compounded continuously. Meanwhile, 15000 dollars is invested in a bank account at an interest rate of 2 percent compounded annually.



To the nearest year, When will the two accounts have the same balance?



The two accounts will have the same balance after ____ years.



Calculus help please!!!! Compound Interest?cheap loans





Let t be the number of years.



Equal the balance after t years,



4000e^.08t = 15000(1.02)^t, where the LHS is the one compounded continuously, while the RHS is the one compounded annually.



Collect variables in one side,



(e^.08/1.02)^t = 15/4



Take ln, and solve for t,



t = ln(15/4)/ln(e^.08/1.02) = 21.96 ~ 22 years



So, the two accounts will have the same balance after 22 years.



Calculus help please!!!! Compound Interest?

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17 years|||I don%26#039;t know what continuously means... but the formula is:



E=S*P^t/c



E= End amount



S= Start amount



P= Percent %26lt;or%26gt; Interest Rate



t = total time



c = time for one cycle (ex. compounded monthy would be 1/12)



^= To the power of



*= multiplied by



/= divided by



Hope this helps|||Compounded contiuously means that you have to use the equation A = Pe^rt. You will substitute P as the dollars invest, r as the percent interest, and t is what you are trying to find. Set the two equations equal to each other, which means:



4000e^(.08t) = 15000e^(.02t) and you can figure this out by taking the natural log on both sides. The nearest year for this would be 22 years. You can substitute in 22 for t in both different equations and the amounts will be very close (this is because it is asking for the nearest year so 22 is a rounded number)

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