The traffic flow rate (cars per hour) across an intersection is r(t)=300+800t120t2\displaystyle {r}{\left({t}\right)}={300}+{800}{t}-{120}{t}^{{2}}, where t\displaystyle {t} is in hours, and t\displaystyle {t}=0 is 6am. How many cars pass through the intersection between 6 am and 10 am?

  cars