how many years will it take $5,500 to grow to $6,300 if it is invested at an annual rate of 2.5% compounded continuously?
A = Pert
A = final amount = 6300
P = beginning amount = 5500
r = rate expressed as a decimal = 0.025
t = time in years = (the unknown)
A = Pert
Solve for t. Divide both sides by P
= ert
Write an equivalent natural log equation using the rule that
X = eY is equivalent to Y = ln(X)
rt = ln
Use the rule of logs ln = ln(X)-ln(Y)
rt = ln(A)-ln(P)
Divide both sides by r
t =
Now substitute the given values
t =
Put that in your TI-83 or TI-84 this way
(ln(6300)-ln(5500))/0.025
Press ENTER
Read 5.432061646 years or about 5 years and 5 months.
Edwin