One of the two buses completes a journey of $300 \, km$ in $7 \frac{1}{2} \, hours$ and the other a journey of $450 \, km$ in $9 \, hours.$ The ratio of their average speed is:

Two cyclists started simultaneously towards each other and meet each other $3$ hours $20$ minutes later. How much time will it take the slower cyclist to cover the whole distance if the first arrived at the place of departure of the second $5$ hours later than the second arrived at the point of departure of the first? (in hours)

$A$ bullock cart has to cover a distance of $80 \text{ km}$ in $10 \text{ hours}$. If it covers half of the journey in $\frac{3}{5}$ of the total time,what should be its speed to cover the remaining distance in the time left? (in $\text{km/h}$)

The ratio of the speeds of a car,a train,and a bus is $5:9:4$. The average speed of the car,the bus,and the train together is $72 \text{ km/h}$. What is the average speed of the car and the train together? (in $\text{km/h}$)

$A$ man covers a certain distance by car driving at $70 \, km/hr$ and he returns to the starting point riding on a scooter at $55 \, km/hr$. Find his average speed for the whole journey in $km/hr$.

Two trains are running at a speed of $40 \, km/h$ and $20 \, km/h$ respectively in the same direction. The fast train completely passes a man sitting in the slow train in $5 \, seconds$. The length of the fast train is (in $m$):