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 A

Explanation:

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.