A tractor mounted ripper will be used for excavating a limestone having a seismic velocity of 1830m/sec. Field tests indicate that the ripper can obtain satisfactory rock fracturing to a depth of 0.61 m with one pass of a single shank at 0.91 m intervals. Average ripping speed for each 152 m pass is 2.4 km/hr. Maneuver and turn time for each pass averages 0.7 min. Job efficiency is estimated at 0.80. Estimate the hourly production (Bm3/h) of excavation