Two trains $100 \; m$ and $120 \; m$ long are running in the same direction with speeds of $72 \; km/h$ and $54 \; km/h$. In how much time will the faster train cross the second (in $; s$)?

$A$ train covers a distance of $12 \;km$ in $10 \;minutes$. If it takes $6$ seconds to pass a telegraph post,then the length of the train (in $m$) is:

$A$ train $125 \;m$ long passes a man,running at $5 \;km/hr$ in the same direction in which the train is going,in $10 \;seconds$. The speed of the train is (in $km/hr$):

How many seconds will a train $60 \; m$ in length,travelling at the rate of $42 \; km/h$,take to pass another train $84 \; m$ long,proceeding in the same direction at the rate of $30 \; km/h$?

$A$ train passes a station platform in $36 \; \text{seconds}$ and a man standing on the platform in $20 \; \text{seconds}$. If the speed of the train is $54 \; \text{km/hr}$, what is the length (in $m$) of the platform?

Length of a train and that of a platform are equal. If with a speed of $135 \; km/hr$,the train crosses the platform in $40 \; seconds$,then the length (in $m$) of the train is: