A man covers half of his journey by train at 90 km/hr, one-third of the remainder by bus at 30 km/hr and the rest by cycle at 10 km/hr. The average speed during the entire journey is ______

Average speed = Total distance/total time

Let us consider total distance =180km

Case 1 :  man covers half of his journey by train at 90 km/hr

               Distance= 90km => time t1=$$\frac{90}{90}$$=1hr

Remaining distance = 90km

Case 2 :  man covers one-third of the remainder by bus at 30 km/hr

                Distance = 30km => time t2=$$\frac{30}{30}$$=1hr

Case 3 : man covers rest by cycle at 10 km/hr

             Distance = 60km => time t3=$$\frac{60}{10}$$=6hr

Therefore Average speed = $$\frac{180}{1+1+6}$$= 22.5km/hr