Question 963867
A principal of 
$1300
 is invested at 
8.75%
 interest, compounded annually. How many years will it take to accumulate 
$4000
 or more in the account?
.
Use:
A = P(1+i)^t
where
A is amount after time t (4000)
P is principal (1300)
i is interest (.075)
t is time (years) -- this is what we're looking for
.
4000 = 1300(1+.075)^t
4000 = 1300(1.075)^t
40 = 13(1.075)^t
40/13 = (1.075)^t
{{{log(1.075,(40/13))}}}  = t
15.54 years = t
answer: approximately 16 years