A car travels in a straight line along a road. Its distance ‘x’ from a stop sign is given as a function of ‘t’ by the equation $\mathrm{x}\left(\mathrm{t}\right) = \mathrm{\alpha t} + {\mathrm{\beta t}}^3$ , where $\mathrm{\alpha } =$ 2.0m/ s, $\mathrm{\beta } =$ 0.01m/ ${\mathrm{s}}^3$ . Calculate the average velocity of the car in the time interval t = 2.00 sec to 4.00 sec.