# Calc1.80

Find the average speed of a car, starting at time 0, if it drives for 5 hours and its speed at time t (in hours) is given by $s(t)=5t^{2}+7t+e^{t}$ in miles per hour.
${\frac {1}{5}}\int _{{0}}^{{5}}5t^{2}+7t+e^{t}\,dx={\frac {1}{5}}\left[{\frac {5}{3}}t^{3}+{\frac {7}{2}}t^{2}+e^{t}\right]_{{0}}^{{5}}={\frac {1}{5}}\left[{\frac {5}{3}}5^{3}+{\frac {7}{2}}5^{2}+e^{5}-1\right]={\frac {1769+6e^{5}}{30}}\approx 88.65\,$ mph