If a train 120 m long passes a tree in 12 seconds, find its speed in km/h

A. 30 km/h
B. 36 km/h
C. 40 km/h
D. 45 km/h

Solution:
Speed = Distance ÷ Time = 120 ÷ 12 = 10 m/s
= 10 × 18/5 = 36 km/h
Answer: B