Abiologist is studying the growth of a particular species of algae. she writes the following equation to show the radius of the algae, f(d), in mm, after d days: f(d) = 9(1.04)d part a: when the biologist concluded her study, the radius of the algae was approximately 12.81 mm. what is a reasonable domain to plot the growth function? (4 points) part b: what does the y-intercept of the graph of the function f(d) represent? (2 points) part c: what is the average rate of change of the function f(d) from d = 3 to d = 9, and what does it represent? (4 points)

Gas mileage actually varies slightly with the driving speed of a car (as well as with highway vs. city driving). suppose your car averages 33 miles per gallon on the highway if your average speed is 54 miles per hour, and it averages 22 miles per gallon on the highway if your average speed is 75 miles per hour. answer parts (a) and (b) below. a. what is the driving time for a 2000-mile trip if you drive at an average speed of 54 miles per hour? what is the driving time at 75 miles per hour? the driving time at 54 miles per hour is nothing hours. (type an integer or decimal rounded to two decimal places as needed.) the driving time is at 75 miles per hour is nothing hours. (round to two decimal places as needed.) b. assume a gasoline price of $3.33 per gallon. what is the gasoline cost for a 2000-mile trip if you drive at an average speed of 54 miles per hour? what is the gasoline cost at 75 miles per hour? the gasoline cost at 54 miles per hour is $ nothing. (round to two decimal places as needed.) the gasoline cost at 75 miles per hour is $ nothing. (round to two decimal places as needed.)