The distance-time graph of a cyclist is shown in the figure. The average speed of the cyclist in the whole journey is ____ $\mathit{km}/\mathit{hr}$.

The distance-time graph of a cyclist is shown in the figure. The average speed of the cyclist in the whole journey is $8\mathit{ km}/\mathit{hr}$.
 Average speed is defined as the ratio of total distance covered by a body to total time taken by the body. The total distance covered by cyclists is $40\mathit{ km}$ and the total time taken is $5 \mathit{hr}$.
     $\mathit{Average\; speed}=\frac{\mathit{total\; distance\; covered}}{\mathit{total\; time\; taken}}$
$\Rightarrow \mathit{Average\; speed}=\frac{40\mathit{ km}}{5 \mathit{hr}}$
$\Rightarrow \mathit{Average\; speed}=8\mathit{ km}/\mathit{hr}$
The average speed of cyclist in the whole journey is $8\mathit{ km}/\mathit{hr}$.