A train moves from P to Q at an average speed of 90km/h and immediately returns from Q to P through the same route at an average speed of 45km/h. Find the average speed for the entire journey

A.

55.00km/h

B.

60.00km/h

C.

67.50km\h

D.

75.00km\h

Correct answer is C

Average speed from P to Q = 90km\h

Average speed from O to P = 45km/h

Average for the entire journey = 90 + 45

\(\frac{135}{2}\) = 67.50 km/h