Logarithms help

av8or91 · #1 $Old$ 04-29-2008, 12:48 PM

If $2000 is invested at a rate of 12 percent per year, what is the principle after 5 years if the interest is compound quarterly? What is the principle afetr 5 years if the interest is compound quarterly?

Thanks to anyone who can solve.

james_bond · #2 $Old$ 04-29-2008, 12:57 PM

Is it $2000\cdot 1.03^{20}=3612.22$ ? (There are $5*4=20$ "compounds" with $12/4=3 \%$ .)
I'm not sure as there are no logarithms in it...

av8or91 · #3 $Old$ 04-29-2008, 02:40 PM

Doesnt the compund interest formula contain logarithms?

icemanfan · #4 $Old$ 04-29-2008, 02:43 PM

Quote:

Originally Posted by av8or91 $View Post$

Doesnt the compund interest formula contain logarithms?

The formula is $A = P(1 + \frac{r}{t})^{nt}$ where r is the annual rate, t is the number of periods per year, n is the number of years, and P is the principal. So there are no logarithms in the formula.

av8or91 · #5 $Old$ 04-30-2008, 01:27 PM

Alright thanks for the reply.

I have one logarithm problem I cant figure out

Log2x^3= Log2(6-x)

topsquark · #6 $Old$ 04-30-2008, 02:01 PM

Quote:

Originally Posted by av8or91 $View Post$

Alright thanks for the reply.

I have one logarithm problem I cant figure out

Log2x^3= Log2(6-x)

New questions go in new threads.

$log_2(x^3) = log_2(6 - x)$

$x^3 = 6 - x$

$x^3 + x - 6 = 0$

There are no "nice" solutions to this equation, so it isn't surprising that you haven't been able to solve it. Numerically I get x = 1.634365293.

-Dan