High concentrations of carbon monoxide CO can cause coma and possible death. The time required for a person to reach a COHb level capable of causing a coma can be approximated by the quadratic model T=.0002x^2−.316x+127.9, where T is the exposure time in hours necessary to reach this level and 500≤ x ≤800 is the amount of carbon monoxide present in the air in parts per million? (ppm).
A) What is the exposure time when x= 600? hr
B) Estimate the concentration of CO necessary to produce a coma in 9 hr.