$A$ gun is fired at a distance of $1.34$ $km$ from Geeta. She hears the sound after $4$ $sec$. The speed at which sound travels is (in $m/sec$):

$A$ man travelled a distance of $80\, km$ in $7\, hours$,partly on foot at the rate of $8\, km/h$ and partly on bicycle at $16\, km/h$. The distance travelled on foot is (in $km$):

What is the length of the bridge (in $m$) that a man riding at $15 \, km/h$ can cross in $5 \, minutes$?

Amit started cycling along the boundaries of a square field from corner point $A$. After half an hour,he reached the corner point $C$,diagonally opposite to $A$. If his speed was $8 \, km/h$,what is the area of the field in square $km$?

Two trains start at the same time from Delhi and Mumbai and move towards each other at the rate of $85 \, km/h$ and $65 \, km/h$ respectively. When they meet,it is found that one train has travelled $20 \, km$ more than the other. Find the distance between Delhi and Mumbai (in $km$).

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)