+128407 OK...we need to use this "formula"
a ) A(t) = P ( 1 + r)^(t)
Where
A(t) is a future amount
P is the beginning amount
r = interest rate expressed as a decimal
t = number of years invested
b) We want to solve this for t
800 = 500 ( 1 + .015)^t divide both sides by 500
800/ 500 = ( 1 + .015)^t take the log of both sides
log ( 800/500) = log ( 1.015)^t and we can write
log ( 800/ 500) = t * log(1.015) divide both sides by log (1.015)
og (800/500) / log (1.015) = t ≈ 31.5 years
