$A$ train $700 \, m$ long is running at a speed of $72 \, km/hr$. If it crosses a tunnel in $1 \, minute$,then the length of the tunnel (in $metres$) is:

Two persons begin together to write out a booklet containing $8190$ lines. The first person starts with the first line,writing at the rate of $200$ lines an hour; and the second person starts with the last line,then writes the $8189^{th}$ line and so on,proceeding backward at the rate of $150$ lines an hour. At what time will they meet (in $.4$)? (in hours)

$A$ speed of $45\, km/h$ is equivalent to which speed in $m/s$?

$A$ train $200 \, m$ long is running at a speed of $20 \, m/s$. In how much time (in $seconds$) will it cross a bridge of $400 \, m$ length?

$A$ $300 \, m$ long train is travelling with a speed of $45 \, km/hr$ when it passes point $A$ completely. At the same time,a motorbike starts from point $A$ with a speed of $70 \, km/hr$. When it exactly reaches the middle point of the train,the train increases its speed to $60 \, km/hr$ and the motorbike reduces its speed to $65 \, km/hr$. How much distance will the motorbike travel while passing the train completely? (in $km$)

If a train,with a speed of $60\, km/hr$,crosses a pole in $30\, seconds$,the length of the train (in $meters$) is