The exponential growth formula is y = ab^x, where b=rate of growth, a=initial value, x=time interval.
Our equation is
P(t) = 18(1.05)^t
We are multiplying our 18 by 1.05 every day--that means t's increasing, and it's growth. Anything lower than 1 (like .95) means decay, and anything over means growth.
1.05 - 1 = .05
<u>So every day the number grows by a factor of .05.</u>
