Answer: A toad population is increasing by about 7.5% each year.
An event organizer finds each year's attendance for the past five years is about 4/5 of the previous year's attendance.
Explanation:
On the highway, Kareem's car gets 38 mpg.
This can be modeled with a linear relationship between the miles and the gallons of fuel needed.
Shu Fang has $25.75 deducted from her checking account every month.
Here we know that each month a constant amount is deducted from her, this is not an exponential relation.
A toad population is increasing by about 7.5% each year.
If the population initially was an amount P, after one year the population is P*1.075, after two years the population is P*(1.075)^2 and so on, this can be modeled with an exponential function where the years variable, the function will have the general form:
Population(y) = P*(1.075)^y
An event organizer finds each year's attendance for the past five years is about 4/5 of the previous year's attendance.
If the first year the population is X, the year after the attendance will be (4/5)X, and the year after this process applies again, so you have a 4/5 of the previous attendance, the attendance now is (4/5)^2*X
This also can be modeled with an exponential function, of the shape:
Attendance (y) = X*(4/5)^y, where again, y means years.
The thing you may notice is that in this case the model only works for the lapse of 5 years that the event organizer said.