Use the data in Exercise 23 of Section 7.1. To locate the points, use the midpoint of each income category; use a value of $25,000 for the category "less than $30,000," and use a value of $70,000 for the category "more than $60,000."
a. Construct a scatterplot and, based on visual inspection, draw the best-fit line by eye.
b. Briefly discuss the strength of the correlation. Estimate or compute r and r2. Based on your value for r2, identify how much of the variation in the variable can be accounted for by the best-fit line.
c. Identify any outliers on the scatterplot and discuss their effects on the strength of the correlation and on the best-fit line.
d. For this case, do you believe that the best-fit line gives reliable predictions outside the range of the data on the scatterplot? Explain.