The motorcyclist drove 90 km at a speed of 30 km / h and then another 40 km. In the same direction at

The motorcyclist drove 90 km at a speed of 30 km / h and then another 40 km. In the same direction at a speed of 20 km / h. What is the average speed along the way.

These tasks: the first segment of the path of the motorcyclist under consideration (S1 = 90 km and V1 = 30 km / h); second leg (S2 = 40 km and V2 = 20 km / h).

Let us define the formula for calculating the desired average speed of the motorcyclist in question: V = S / t = (S1 + S2) / (t1 + t2) = (S1 + S2) / (S1 / V1 + S2 / V2).

Calculation: V = (90 + 40) / (90/30 + 40/20) = 130 / (3 + 2) = 130/5 = 26 km / h.

Answer: The motorcyclist in question was moving at an average speed of 26 km / h.