When a factory operates from 6am to 6pm, its total fuel consumption varies according to the formula f(t)= 0.6t2-0.4t0.6+13 Where t is the time in hours after 6 am and f(t) is the number of barrels of fuel oil.

What is the average rate of consumption from 6 am to 2pm? Please round your answer to 2 decimal places.

_______ barrels per hour