The speed of sound traveling through ocean water with salinity 35 parts per thousand has been modeled by the equation below where c is the speed of sound (in meters per second), t is the temperature (in degrees celsius), and d is the depth below the ocean surface (in meters). c = 1449.2 + 4.6t − 0.055t2 + 0.00029t3 + 0.016d a scuba diver began a leisurely dive into the ocean water; the diver's depth and the surrounding water temperature over time are recorded in the following graphs. estimate the rate of change (with respect to time) of the speed of sound through the ocean water experienced by the diver 20 minutes into the dive. what are the units?