Question

A railway passenger counts
the telegraph posts on the line as he passes them. If they are 50
metres apart and the train is going at 48 km per hour, how many posts
will he cross per minute?

Answer 1

his speed is 48kmph
60 minutes he goes 48000m
1 minute he will go 48000/60
                            =800m

In 800 m no of telegraph posts is 800/50 ...........(since they are 50m apart) 
                                                =16

So he will cross 16 telegraph posts per minute.

Answer 2

speed = 48 km / hour

distance in meres = 48000 m

distance travelled in one minute = 48000/60

= 800 m

therefore number of posts = 800/50

= 16 posts.