Question

a man in a train notices that he can count 21 telephone posts in one minute.if they are known to be 50 meters apart,at what speed is the train travelling

it is direct and inverse variation

Answer 1

If he can count 21 poles each 50m apart that means that the total distance is 20*50m=1000m=1km

time is 20 minutes=1/3 hours

speed is distance/ time
speed=1/(1/3)=3km/h