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?  Choose the correct answer:
A) 60km/hr	B) 54km/hr	C) 50km/hr	D) 45km/hr	E) 62km/hr
Number of gaps between 21 telephone posts = 20   distance travelled in 1 minute = 50*20= 
<gadget id="calculator">50*20</gadget>
<output>1_000</output>
1000m= 1km   speed = 60km/hr   60km/hrnswer is 60km/hr
<result>A</result>
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?