SOLUTION: Find the number of years it will take for $31,000 to grow to 33,405.06 at 3% interest compounded quarterly. I am going wrong somwhere toward the end of the problem. We have to use

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: Find the number of years it will take for $31,000 to grow to 33,405.06 at 3% interest compounded quarterly. I am going wrong somwhere toward the end of the problem. We have to use       Log On


   



Question 275383: Find the number of years it will take for $31,000 to grow to 33,405.06 at 3% interest compounded quarterly. I am going wrong somwhere toward the end of the problem. We have to use the graphing calculator. We don't have to graph it, but just use the calculator to find the answer. I get all the way down to the end. Where it will ask to solve for t. It comes down to
log(1.08)/4log(1.0075)=t
I entered it in the calculator exactly like this log(1.08)/4log(1.0075) My answer comes out to 2.711547965E-5. It says round to the nearest tenth and when I put down 2.7 I got it wrong. It came out to 2.5. Where could I be going wrong? Thanks....
PS: Also how do I thank a tutor for their help? I can't find how to leave feedback.

Found 2 solutions by scott8148, ankor@dixie-net.com:
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
33405.06 = 31000 (1 + .0075)^(4t)

1.0776 = 1.0075^(4t)

{[log(1.0776)] / [log(1.0075)]} / 4 = t


this works
you probably needed to carry the calculations to more places


not sure about giving feedback ... have only gotten it

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Find the number of years it will take for $31,000 to grow to 33,405.06 at 3% interest compounded quarterly.
:
Let's see what I get:
:
The compound interest formula: A = P%281+%2B+%28r%2Fn%29%29%5E%28nt%29%29
Where
A = resulting amt
P = principal
r = interest rate in decimal form
n = no. times compounded per year
t = no. of years
:
31000%281+%2B+%28.03%2F4%29%29%5E%284t%29%29 = 33405.06
31000%281.0075%29%5E%284t%29%29 = 33405.06
%281.0075%29%5E%284t%29%29 = 33405.06%2F31000
%281.0075%29%5E%284t%29%29 = 1.0775826
log%281.0075%29%5E%284t%29%29 = log(1.0775826)
4t*log(1.0075) = log(1.0775826)
4t = log%281.0775826%29%2Flog%281.0075%29; use the calc here
4t = 10.00
t = 10%2F4
t = 2.5 yrs