The average speed of a vehicle on a stretch of Route 134 between 6 a.m. and 11 a.m. on a typical weekday is approximated by the function F(t) = 22t - 44√(t) + 48 (0
where f(t) is measured in miles per hour and t is measured in hours, with t=0 corresponding to 6 a.m. Find the interval where f is decreasing and the interval where f is increasing.