Answer:
Exponential growth ; y = 40 * 2^t
Step-by-step explanation:
The scenario above is best modeled using the exponential growth formula.
Since the number of bacteria increases; then it is a growth function.
Number doubles every hour, thus gives the rate of increase.
Exponential growth relation :
y = A(1 + r)^t
A = initial amount of bacteria = number of bacteria in Joanne puts in petri dish = 40
y = amount of bacteria after time t,
(1 + r) = 2
Therefore,
y = 40 * 2^t
