Some types of algae have the potential to cause damage to river ecosystems. The accompanying data on algae colony density (y) and rock surface area (x) for nine rivers are a subset of data that appeared in a scatterplot in a paper in the journal Aquatic Ecology (2010: 33€“ 40).

Cubic meter of air) and the cost of medical care per person over age 65 for six geographical regions of the United States.
a. Compute the equation of the least squares regression : line.
b. What is the value of r2 for this data set? Write a sentence interpreting this value in context.
c. What is the value of se for this data set? Write a sentence interpreting this value in context.
d. Is the linear relationship between rock surface area and algae colony density positive or negative? Is it weak, moderate, or strong? Justify your answer.

x 50 55 50 79 44 37 70 45 49 152 48 22 35 38 171 13 185 25