The traffic flow rate past a certain point on a highway is q(t)=1200+2000t−300t^2 where t is in hours and t=0 is 8 am. how many cars pass by during the time interval from 8 to 11 am?

Well, as far as I can tell, is just an "average rate of change" issue, which is just a slope value

so, at 8am, t=0, 11am is 3hrs later, so t = 3

so in short, what's the average rate from 8-11am or for t = 0 to t=3?

well