1. Civil engineers use regression analysis to estimate repair and replacement costs of different types of piping. The interdependent variable in their analysis, X, is the diameter of the pipe( in millimeters). Data for a sample of 13 different pipe sizes is shown in the table.

Ratio

6.58 6.97 7.39 7.61 7.78 7.92 8.20 8.42 8.60 8.97 9.31 9.47 9.72

Diameter

80 100 125 150 200 250 300 350 400 450 500 600 700

Find the least squares line relating ration of repair to replacement cost (y) to pipe diameter(x).

a. y=6.33+.0238x

b. y=6.18 + .0013x

c. y=6.91+.0122x

d. y=6.67+.0048x