<h2>
Answer with explanation:</h2>
We know that the exponential function is given by:

where a is the initial amount.
and b is the change in the amount and is given by:
if the function is increasing by a rate of r
and
if the function is decreasing by a rate of r.
a)
The initial amount of fish in the trout are: 7
i.e. a=7
Also, the population doubles every year.
This means that that b=2
Hence, the population after t years is given by the function P(t) as:

b)
The original amount of the machine is: $ 3,000
i.e. a=3,000
Also, the value of machine decreases by a rate of 7%
i.e.

Hence, we have:

Hence, the function which represent the price of the machine after t years i.e. P(t) is given by:

c)
The initial population of colony of ants i.e. a=300.
The number of ants increases at a rate of 1.5% every month.
i.e. 
i.e.

Hence, the function P(t) which represents the population of ants after t months is given by:

d)
The initial infected cells i.e. a=300
The infected cells are decaying at a rate of 1.5% per minute.
i.e.

Since, there is a decay hence,

Hence, the function P(t) which represents the number of infected cells after t minutes is given by:
