Level curves for barometric pressure (in millibars) are shown for 6:00 a.m. on a day in November. A deep low with pressure 972 mb is moving over northeast Iowa. The distance along the red line from K (Kearney, Nebraska) to S (Sioux City, Iowa) is 300 km. 10120161020 1012 1008 1004 1000- 1024 996 992- 988- 984. 980 976 K 1008 What are the units of the directional derivative? mb/km km O mb/km km/mb mb Estimate the value of the directional derivative of the pressure function at Kearney in the direction of Sioux City. (Round your answer to two decimal places.)