3. Assume that the level of nitrogen dioxide present in the atmosphere on a certain June day:r in cityA is given by N (r) = 0.05:3\" 6? + 53 (0 g r 5 3) where Nit} is measured in pollutant standard index [PSI] and t is measured in hours, with t = 0 corresponding to Tam. Find the rate at which the level of nitrogen dioxide was changing at 9 am. 4. Find the second derivative of the function. Simplify if possible. \"0:; :2 +5