$A$ farmer travelled a distance of $61 \, km$ in $9 \, hours$. He travelled partly on foot at $4 \, km/h$ and partly on bicycle at $9 \, km/h$. The distance travelled on foot is (in $km$)

$A$ man takes $6$ hours $30$ minutes in walking to a certain place and riding back. He would have gained $2$ hours $10$ minutes by riding both ways. How long would he take to walk both ways? (in minutes)

$P$ and $Q$ are $27 \, km$ apart. Two trains with speeds of $24 \, km/h$ and $18 \, km/h$ respectively start simultaneously from $P$ and $Q$ and travel in the same direction. They meet at a point $R$ beyond $Q$. The distance $QR$ is (in $km$):

The wheel of an engine is $3 \frac{3}{4}$ metres in circumference and makes $4$ revolutions in $2$ seconds. The speed of the train is (in $km/h$):

Mohan walks from Tilak Nagar to Moti Nagar and back in a certain time at the rate of $3 \frac{1}{2} \, km/h$. But,if he had walked from Tilak Nagar to Moti Nagar at the rate of $3 \, km/h$ and back from Moti Nagar to Tilak Nagar at the rate of $4 \, km/h$,he would have taken $10 \, minutes$ longer. The distance between Tilak Nagar and Moti Nagar is (in $km$)

$A$ man crosses a stationary bus in $18\, s$. The same bus crosses a pole in $4\, s$. What is the ratio of the speed of the bus to the speed of the man?