A pedestrian walked for 3 hours at a speed of 2 km / h and 1 hour at a speed of 6 km / h. Find the average speed of a pedestrian.

Average pedestrian speed:
Vav. = S / t, where S is the total path traveled by the pedestrian (S = S1 + S2), t is the total travel time (t = t1 + t2, where t1 = 3 hours, t2 = 1 hour).
Distance covered S1 and S2:
S1 = V1 * t1, S2 = V2 * t2, where V1 is the speed in the first section (V1 = 2 km / h), V2 is the speed in the second section (V2 = 6 km / h)
Average travel speed:
Vav. = S / t = (S1 + S2) / (t1 + t2) = (2 * 3 + 1 * 6) / (3 + 1) = 12/4 = 3 km / h.
Answer: The average speed of a pedestrian is 3 km / h.