Two processes for hydraulic drilling of rock are dry drilling and wet drilling. In a dry hole, compressed air is forced down the drill rods to flush the cuttings and drive the hammer; in a wet hole, water is forced down. An experiment was conducted to determine whether the time y it takes to dry drill a distance of 5 feet in rock increases with depth x (The American Statistician, Feb. 1991). The results for one portion of the experiment are shown in the table. Conduct a complete simple linear regression analysis of the data, including a residual analysis. Interpret the results, practically.

Transcribed Image Text:

DRILLROCK Time to Drill 5 Depth at Which Drilling Begins x, feet Feet y, minutes 4.90 25 7.41 50 6.19 75 5.57 100 5.17 125 6.89 150 7.05 175 7.11 200 6.19 225 8.28 250 4.84 275 8.29 300 8.91 325 8.54 350 11.79 375 12.12 395 11.02