The average acceleration is given by:
[tex]a=\frac{v_f-v_0}{t}[/tex]In this case the initial velocity is zero, the final velocity is 13 m/s and the time is 6.4 s. Plugging these values we have:
[tex]\begin{gathered} a=\frac{13-0}{6.4} \\ a=2.03 \end{gathered}[/tex]Therefore, the acceleration is 2.03 m/s²