I have a two part question, I believe part one is correct... I am stuck on how to do part two... if you could help walk me through the steps, I would appreciate it.

5. The data provided is that for the depth of water in Cokato Creek, as measured during a day-long rainstorm. D(t) is a differentiable function of time t. t (hour) | o 4 8 12 16 20 24 D(t) (in) 32 36 38 37 35 33 32 a. Find the approximate value of D '(16). Indicate units of measure and explain its meaning in context of the problem. 4 pointsa D' ( 16 ) = D ( tz ) - D(tis 33 - 37 20- 12 - 4 = - 0. 5 The depth of the water decreases at a rate of 0.5in per hour over the 16th hourb. Cokato High School math students have determined that the function D (t) = 35 - 3cos models the depth of the water during such rain events. D(t) represents the depth of the creek, in inches, after t hours. Use your graphing calculator to find D '(16) and explain the meaning of your answer, with appropriate units, in context of the