Question: Average speed of a highway vehicle the average speed of a vehicle on a stretch of route 134 between 6 a.m. And 10 a.m. On a typical weekday is approximated by the function
f(t) = 20t - 40√t + 50 (0 ≤ t ≤ 4)
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 increasing and the interval where f is decreasing and interpret your results.