A pedestrian walked at a speed of 3.6 kph / h for three quarters of the time of his movement.

A pedestrian walked at a speed of 3.6 kph / h for three quarters of the time of his movement. In the remaining time, he moved at a speed of 5.2 km / h. Determine the average speed of a pedestrian

Initial data: t1 (time of movement in the first section) = 0.75t; V1 (speed in the first section) = 3.6 km / h; t2 (time of movement in the second section) = t – 0.75t = 0.25t; V2 (speed in the second section) = 5.2 km / h.

Let’s define the formula for calculating the average pedestrian speed: Vav. = S / t = (S1 + S2) / t = (V1 * t1 + V2 * t2) / t = (V1 * 0.75t + V2 * 0.25t) / t = 0.75V1 + 0.25V2.

Let’s calculate: Vav. = 0.75 * 3.6 + 0.25 * 5.2 = 4 km / h.

Answer: The average speed of a pedestrian was 4 km / h.