So, to set up your equation is the hardest part. If you remember the basic format, you're set.
I(t) = P * (1+r%)^t
t= time and this will be our variable
Initial amount P = $2740
Rate = 4.3% which converts numerically into .043
I(t) = 7000
Before we get to find out how to find how many years it takes to get to $7000, set up the basic equation by plugging in what we know.
I(t) = $2740(1+4.3%)^t
I(t)=2740(1.043)^t
Now plug in for $7000 for I(t)
7000=2740(1.043)^t Divide both sides by 2740
7000/2740 = 2740/2740(1.043)^t
2.55474453=(1.043)^t
Now you can solve for t in two ways. You can either use the natural log or graph it on your graphing calculate and see when the two equations meet.
In your calculator you can set up:
ln(2.55474453)/ln(1.043) = t which is the method I prefer since it's much simpler
t=22.278528
but you can also graph it in your ti-84
with
y1=2.55474453
y2=(1.043)^x
and find where they intersect on the graph.
either way it'll be the same answer
