$A$ train crosses a platform in $30 \, s$ travelling with a speed of $60 \, km/h$. If the length of the train is $200 \, m$, then the length of the platform is (in $m$):

$A$ cyclist,after cycling a distance of $70 \,km$ on the second day,finds that the ratio of distance covered by him on the first two days is $4:5$. If he travels a distance of $42 \,km$ on the third day,then the ratio of distances travelled on the third day and the first day is:

$A$ student walks from his house at a speed of $2 \frac{1}{2} \text{ km/h}$ and reaches his school $6 \text{ min}$ late. The next day,he increases his speed by $1 \text{ km/h}$ and reaches $6 \text{ min}$ before school time. How far is the school from his house? (in $\text{km}$)

Two men start together to walk a certain distance,one at $4 \, km/h$ and another at $3 \, km/h$. The former arrives half an hour before the latter. Find out the distance in $km$.

If $A$ travels to his school from his house at the speed of $3 \, km/h$,he reaches the school $5 \, minutes$ late. If he travels at the speed of $4 \, km/h$,he reaches the school $5 \, minutes$ earlier than the scheduled time. The distance of his school from his house is (in $km$):

$A$ man travels $360 \, km$ in $4 \, hrs$,partly by air and partly by train. If he had travelled all the way by air,he would have saved $\frac{4}{5}$ of the time he was in train and would have arrived at his destination $2 \, hrs$ early. Find the distance he travelled by train (in $km$).