Pipes used in a water distribution network are susceptible to breakage due to a variety of factors. When pipes break, engineers must decide whether to repair or replace the broken pipe. A team of civil engineers used regression analysis to estimate y = the ratio of repair to replacement cost of commercial pipe in the IHS Journal of Hydraulic Engineering (September 2012). The independent variable in the regression analysis was x = the diameter (in millimeters) of the pipe. Data for a sample of 13 different pipe sizes are provided in the table.

a. Construct a scatterplot for the data.

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

c. Plot the least squares line on the graph, part a.

d. Interpret, practically, the values β̂_o and β̂₁.

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WATERPIPE DIAMETER RATIO 80 6.58 100 6.97 125 7.39 150 7.61 200 7.78 250 7.92 300 8.20 350 8.42 400 8.60 450 8.97 500 9.31 600 9.47 700 9.72