From the table:
When time;
[tex]t_1=0\text{ s}[/tex]
The position;
[tex]x_1=20\text{ m}[/tex]
And when time,
[tex]t_2=4\text{ s}[/tex]
The position;
[tex]x_2=40\text{ m}[/tex]
The average velocity is given as,
[tex]\begin{gathered} v_{av}=\frac{\text{ total displacement}}{\text{ total time taken}} \\ =\frac{x_2-x_1}{t_2-t_1} \end{gathered}[/tex]
Substituting all known values,
[tex]\begin{gathered} v_{av}=\frac{(40\text{ m})-(20\text{ m})}{(4\text{ s})-(0\text{ s})} \\ =5\text{ m/s} \end{gathered}[/tex]
Therefore, the average velocity at t=4 s is 5 m/s.
