Find the best-fitting straight line to the given set of data, using the method of leasts squares. Find the correlation coefficient.

(a)

Best fitting line:

Correlation coefficient:

(b)

Best fitting line:

Correlation coefficient:

(c)

Best fitting line:

Correlation coefficient:

(d)

Best fitting line:

Correlation coefficient:

**Cost Curve**: Dean (*Statistical Cost Estimation*, Bloomiington, Ind.: Indiana University Press, page 342) made a statistical estimation of the cost-output relationship for a shoe store. The data for the firm is given in the following table.

4.5, 7, 9, 10, 15, 20, 33, 50

3, 3.3, 3.4, 3.5, 4.5, 5.5, 7.5, 12

Here, is the output in thousands of pairs of shoes, and is the cost in thousands of dollars. (a) Determine the best fitting line using least squares.

(b) Determine the best-fitting quadratic using least squares.