The speed of a runner increased steadily during the first three seconds of a race. Her speed at half-second intervals is given in the following table: $$\begin{array}{|c|c|c|c|c|c|c|c|}\hline t\ (\textrm{s}) & 0 & 0.5 & 1.0 & 1.5 & 2.0 & 2.5 & 3.0 \\ \hline v\ (\textrm{ft}/\textrm{s}) & 0 & 6.2 & 10.8 & 14.9 & 18.1 & 19.4 & 20.2 \\ \hline \end{array}$$ Find lower and upper estimates for the distance (in feet) that she traveled during these three seconds.

Lower estimate = feet

Upper estimate = feet