2.78 College students by state. Refer to Exercise 2.75, where you examined the relationship between the number of undergraduate college students and the populations for the 50 states. Figure 2.21 gives the output from a software package for the regression. Use this output to answer the following questions:

1. (a) What is the equation of the least-squares regression line?

2. (b) What is the value of r²?

3. (c) Interpret the value of r².

4. (d) Does the software output tell you that the relationship is linear and not, for example, curved? Explain your answer.