1) A man in a train notices that he can count 21 telephone posts in one minute. If they are known to be 50 metres apart, then at what speed is the train travelling ? A) 60 km/hr B) 70 km/hr C) 50 km/hr D) 40 km/hr E) 90 km/hr Answer: Option AExplanation:Number of gaps between 21 telephone posts = 20. Distance travelled in 1 minute $=(50\times 20)$ m = 1000 m = 1 km. $\therefore$ Speed = 60 km/hr.
