The boy, moving evenly, walked 5 km at a speed of 2.5 km / h for the next 5 km in 3 hours.

The boy, moving evenly, walked 5 km at a speed of 2.5 km / h for the next 5 km in 3 hours. Find the boy’s average speed along the way.

These tasks: the first section of the boy’s path (S1 = 5 km; V1 = 2.5 km / h); the second section of the boy’s path (S2 = 5 km; t2 = 3 hours).

Let’s define the formula for calculating the average speed of the boy over the entire distance traveled: Vav. = (S1 + S2) / (t1 + t2) = (S1 + S2) / (S1 / V1 + t2).

Let’s calculate: Vav. = (5 + 5) / (5 / 2.5 + 3) = 10/5 = 2 km / h.

Answer: The boy had to move at an average speed of 2 km / h.