Answer
$1330$ calories
Work Step by Step
To find the total energy required, we need to calculate the time it takes to complete the marathon and then multiply by the energy expenditure rate.
Calculate time to complete the marathon:
$\text{Time}=\frac{26.2\text{ miles}}{13.1\text{ mph}}=2.0\text{ hours}$
Determine the number of calories:
$\text{Energy}=2.0\text{ hours}\times 665\text{ calories/hour}=1330\text{ calories}$
