Problems on Average Speed

A train runs from Howrah to Bandel at an average speed $20 \mathrm{kmph}$ and returns at an average speed of $30 \mathrm{kmph}$. The average speed (in $\mathrm{kmph}$) of the train in the whole journey is _____

A man goes to a certain place at a speed of $48 \mathrm{kmph}$. and returns at a speed of $32 \mathrm{kmph}$. Find the average speed of the journey.

One-fifth of the certain journey is covered at the rate of $20$ Km/h, one-fourth at the rate of $50$ Km/h, and the rest at $55$ Km/h. Find the average speed for the whole journey.

A car has an average speed of $60 \mathrm{km}/\mathrm{hr}$ while going from Delhi to Agra and has an average speed of$y \mathrm{km}/\mathrm{hr}$ while returning to Delhi from Agra (by travelling the same distance). If the average speed of the car for the whole journey is $48 \mathrm{km}/\mathrm{hr}$, then what is the value of $y$?

A man completes $30 \mathrm{km}$ of a journey at $6 \mathrm{km}/\mathrm{h}$ and the remaining $40 \mathrm{km}$ in $5 \mathrm{h}$. His average speed for whole journey is:

An aeroplane flies around squares whose sides are of length $100$ miles. If the aeroplane hovers at a speed of $100 \mathrm{mph}$ the first side, $200$ $\mathrm{mph}$ the second side, $300$ $\mathrm{mph}$ the third side and $400 \mathrm{mph}$ the fourth side. The average speed of the aeroplane around the square is