A tourist covers half of his journey by train at 60 km/h, half of the remainder by bus at 30 km/h and the rest by cycle at 10 km/h. The average speed of the tourist in km/h during his entire journey is
(A) 36
(B) 30
(C) 24
(D) 18
Answer: (C)
Explanation: Let total distance be D
Total Time = D(1/2*60 + 1/4*30 + 1/4*10) = D/24
Average Speed = Total distance / Total time = 24