4. A study of air quality in a particular city by an environmental group suggest that t years from now the level of carbon monoxide, in parts per million , in the air will be A=0.2t^2+.01t+5.1.
4a. What is the current level of Carbon Monoxide, in part per million?
4b. How many years from now will the level of carbon monoxide be at 8 parts per million? Round to the nearest tenth.