Problems on Average Speed

Distance between two stations $\mathrm{x}$ and $\mathrm{y}$ is $778 \mathrm{km}$. A train covers the journey from $\mathrm{x}$ to $\mathrm{y}$ at a speed of $84 \mathrm{kmph}$ and returns to $\mathrm{x}$ with a speed of $56 \mathrm{kmph}$. Find the average speed of the train (in $\mathrm{kmph}$) for the whole journey.

A Particle Moves with a Speed of $2 \mathrm{m}/\mathrm{s}$ for $20 \mathrm{s}$. It Again Moves with a Speed of $4 \mathrm{m}/\mathrm{s}$ for another $20 \mathrm{s}$ and Finally Moves with a Speed of $6 \mathrm{m}/\mathrm{s}$ for Next $20 \mathrm{s}$. Calculate the Average Speed of the Particle? $(\text{in} \mathrm{m}/\mathrm{s})$

A Particle Moves with a Speed of $4 \mathrm{m}/\mathrm{s}$ for $20 \mathrm{s}$. It Again Moves with a Speed of $6 \mathrm{m}/\mathrm{s}$ for another $20 \mathrm{s}$ and Finally Moves with a Speed of $8 \mathrm{m}/\mathrm{s}$ for Next $20 \mathrm{s}$. Calculate the Average Speed of the Particle? $(\text{in} \mathrm{m}/\mathrm{s})$

A man travelled a distance of $80 \mathrm{km}$ in $7$hours partly on foot at the rate of $8 \mathrm{km}/\mathrm{h}$and partly on bicycle at $16 \mathrm{km}/\mathrm{h}$. Find the distance travelled on foot.