A person covers a certain distance by bus at 45 km/h and immediately returns to the starting point by car at a speed of 80 km/h. What is his average speed during the whole journey?

57.6 km/h 63.2 km/h 73.5 km/h 45.5 km/h

57.6 km/h

Average speed = \(\frac{2 × S1 × S2 }{S1 + S2}\) = \(\frac{2 × 80 × 45 }{80 +45}\) = \(\frac{7200 }{125}\) =   57.6 km/h