A biologist 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) = 11(1.01)d
Part A: When the biologist concluded her study, the radius of the algae was approximately 11.79 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 = 2 to d = 7, and what does it represent?
Answers
Answer:
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Given:
f(d) = 11(1.01)d
To Find:
Part A: When the biologist concluded her study, the radius of the algae was approximately 11.79 mm. What is a reasonable domain to plot the growth function?
Part B: What does the y-intercept of the graph of the function f(d) represent?
Part C: What is the average rate of change of the function f(d) from d = 2 to d = 7, and what does it represent?
Solution:
Part A:
11.79 =
= 11.79/11
= 1.071818
d = log 1.071818 / log 1.01
d = 6.97
Part B:
y-intercept is obtained when domain = 0
d = 0 ⇒ f(0) = = 11 x 1 = 11
f(d) = 11
Part C:
Average rate of change,
Δf/Δd = (f(7) - f(2)) / (7 - 2)
= ( - ) / 5
= 0.57 / 5 = 0.114
Hence, reasonable domain to plot the growth function is 6.97, the y-intercept of the graph of the function f(d) represents f(d) = 11 and the average rate of change of the function f(d) from d = 2 to d = 7 is 0.114.