$A$ particle moves along a straight line along the $x$-axis. Its position $(x)$ versus time $(t)$ graph is shown in the figure [$x$ in meters and $t$ in seconds]. Its average speed during this motion is (in $\text{ m/s}$)

$A$ car travels $\frac{1}{3}$ of the total distance on a straight road at a speed of $20 \, km/hr$ and the remaining distance at a speed of $60 \, km/hr$. What is the average speed of the car in $km/hr$?

$A$ car travels from $A$ to $B$ at a speed of $20\,km/hr$ and returns at a speed of $30\,km/hr$. The average speed of the car for the whole journey is............$km/hr$

Velocity of an object in rectilinear motion is given as a function of time by $v = t - t^3$,where $v$ is in $m/s$ and $t$ is in seconds. Its average velocity over the time interval from $t = 0 \ s$ to $t = 2 \ s$ is ........ $m/s$.

$A$ man walks on a straight road from his home to a market $2.5 \; km$ away with a speed of $5 \; km \; h^{-1}$. Finding the market closed,he instantly turns and walks back home with a speed of $7.5 \; km \; h^{-1}$. What is the magnitude of average velocity in $m/s$?

$A$ particle travels half of the distance of a straight journey with a speed $6 \,m/s$. The remaining part of the distance is covered with speed $2 \,m/s$ for half of the time of the remaining journey and with speed $4 \,m/s$ for the other half of the time. The average speed of the particle is ....... $m/s$.