A vessel departed from point A at 1206 with a counter reading of 606729 and arrived at point B with a counter reading of 731929 at 1148 the following day the vessel is equipped with 20 foot 8inch dia propeller with a pitch of 20 feet. the observed distance at 404.16 miles was covered at an observed speed of 16.85 knots.what should be the apparant slip for this trip?