The concentration of particulate matter (in parts per million) t hours after a factory ceases operation for the day, is given by the following formula, C(t). Find the average concentration for the period from t = 0 to t = 5 25 In (t+ 7) C (t ) = ( 1 + 7 ) 2 The average concentration of particulate matter, for the time period from t = 0 to t =5, is approximately parts per million. (Do not round until the final answer. Then round to four decimal places as needed.)